The market for expensive luxuries collapsed, of course, and the scientists shut down the wars and their factories and bases post haste. The economy got busy shifting resources to sustainable technology as fast as full employment could take it. Status flipped almost overnight, from expensive luxuries to doing more with less. Men who would not have been caught dead in a Prius in 2019 were showing off their electric bicycles by 2021. The advertising folk found their jobs much easier as soon as they turned to public-service education, instead of pushing bad bargains. They were backed up by ubiquitous cameras, showing that public officials were not cheating and consuming more themselves. Overall, we had more unity than a nation at war, with the whole world eager to fix the previous damage before it could continue impoverishing the next generation.
True to the spirit of science, things were built hastily, not for deliberate obsolescence, but with the assumption that even better designs would often arise. We resisted the temptation to mandate electric vehicles, setting performance goals instead. This saved millions of machines from being junked, simply by switching to synthetic oil. It can be made from just wind and air, and the facilities can be tweaked to sequester some carbon long-term as their environmental tax. New vehicles were mostly electric, but not at all like their predecessors. Anything under 50% payload felt like a pretentious waste, so the electric bikes spawned all-weather velomobiles, and small robots soon delivered the packages.
In the general re-shuffling and re-building, the need for transportation went down drastically, due to everything from buying locally to living close to work, etc. Saving energy was always a good reason to change zoning. To leave the neighbourhood, the most popular option became taking one's own personal pod as usual, or a small family model with the kids, pedaling enough for convenient exercise on city streets, and keeping up with traffic on the booster. At the expressway entrance, the roadway electronics take over and accelerate the pods into the first passing gap in a tight "convoy" of mixed passenger pods and freight. Punching in an exit, everyone gets to relax for some screen time while their batteries re-charge en route. Then, local roads from the exit lead to much smaller parking lots, with chargers. "Conference cars" are still easy to transfer into and rent for people travelling together, but a simple A-V hookup between pods is more popular.
Everyone shared ideas through the 'net and tried to avoid duplication, either assisting in making experiments stronger, or branching out in new ways instead. The best rewards were not money, although it got easier to get grants after success, but just being an early poster or adopter of a successful idea. It was a renaissance of rationality, and a rout for rationalization. In every field, any attempt to control the debate rather than win it reminded people of the crazy times, and backfired. It turned out that the same bean counters who had squeezed their fellow employees for profits only had to have their instructions changed to do quite good work, managing co-ops and so on. They even got invited to parties, and not just for the amusement value of their dancing.
The shrunken aviation lobby decided that they could share the skies with power kites, which led to another swift drop in electricity prices. The giant wind turbines got a bit more elegant in design, but were no longer the big growth sector. Instead, huge, foil-shaped kites started drawing figure 8s in the sky as they pulled a tank full of water to an upper reservoir, and then floated to coast the tank back down for another load. The electric generators just run on demand, as hydro power always has. Offshore, all the old windmill foundations were soon scrapped in favour of moorings and other cable-based structures, harvesting both wind and ocean currents.
We will probably never stop arguing about the convoluted border, but we did manage to return about half the planet to wilderness, even giving up some prime farmland for the critters that needed it. With large, unbroken territories, the old top predator was re-introduced to this "parkland" - humans. The only proviso is that they must not use modern technology in their economy - only information crosses the border easily. The remnants of all surviving tribes found new homes similar to their traditional ones for those who preferred the old ways, while some made the jump to the era of agriculture and clocks.
Quite a few rugged individualists and die-hard carnivores went to the wilderness for a while, but then one viral song sparked a revolution in the social sciences. "God's Mixing Board" was a whimsical, almost childish ditty about human variations, and suddenly we all felt easier about being ourselves, while realizing how different others are too. The civil-rights crowd realized that their issue was one of maintenance, not victory, which changed the dynamic completely. We are born with different basic xenophobia settings, so those with a lot of it won't ever be comfy in a multicultural setting, but it is not dangerous letting them set the rules in their own town, as long as they don't hoard the best stuff or force others to compromise. We realized that the key to good social engineering is to plan for variety and change, rather than a prescribed conformity. "World Government" now looks more like safe anarchy than a planned society.
Local autonomy also saved thousands of traditional cultures and languages from the melting pot of cities and open towns. This turned out to be a huge boon to anthropology as well. People taking buyouts were usually glad to move to a town or neighbourhood they preferred anyway. Allowing prejudice to operate, but at short range only, turned into a win-win. As well as the xenophobes, surviving ethnic sub-cultures, and minor religions, there were many communities formed around agreeing to disagree with the majority on everything from the hollow earth to the merits of massacres. Some could have been dangerous, if not for a neatly-engineered treaty system. As long as they only sent out propaganda, not coercion, they enjoyed protection from whatever their particular fear was. However, if a rival group caught them breaking the rules, they could sue and receive the fines levied. Very few would risk that, and none succeeded in going rogue.
Without the plutocrats promoting divisions and war, and with systems engineers working alongside social scientists, our co-operative instincts blossomed. Mechanization never paused, but neither did it get easier for the humans still involved. They got fed up with the people who were only there for a paycheque getting in the way, and were glad to endorse a guaranteed annual income for them. Essential work, with the drudgery gone, became a creative pleasure and a privilege to be earned with talent. To take more pay home would have seemed greedy after getting to play with big stuff all day. Non-essential work remained popular, as a continuum with entertainment. "Look at me" never gets old. 3-D printing customized most everyday objects, but hand craftsmanship has deep psychic roots, and continued to produce masterpieces, even though they often sold for the cost of the materials to whoever loved them most.
Architects and builders got busy making mansions into apartments, and integrating living spaces into shopping and office buildings. The urban farmers settled on a compromise of having fresh greens, but sharing the sunshine with people and laundry, so making salad from the house plants to prune them became common, and the concrete jungles greened up nicely. As with language and culture, traditional-looking houses were preserved, sometimes with efficiency retrofits. The experimental new buildings with zero energy needs for comfort ran from classic facades to junkyard tech, but soon enough the modern esthetic emerged, with the glass and thermal mass arranged to enclose spacious-feeling, well-lit, low-cost homes. The old houses with chimneys, once seen as the only way to live, are now just museum curiosities.
Quite a bit of re-building was needed due to storms and flooding, of course, and the climate changes were even harder on farming and nature. We realized that the glaciers had been guiding the weather as well as moderating it, and made restoring the ice basic to the economy. Taxes stayed at wartime levels, and most tax breaks were based on alternate ways to draw down greenhouse gasses. We put up with any pollution that increased cloud cover, making for some gloomy decades, but overall, geo-engineering was mostly management, except for collecting greenhouse gasses. That was done on a vast scale, using about half the renewable energy generated, even though the actual collection became easy with selective molecules to simply pull it out of the passing breeze. In the US, Glacier National Park became the talisman. Reputations were staked on seeing the ice grow before vanishing entirely. It was a near thing, but we managed it by 2097.
Without the constant demands of stockholders on everything, and their pernicious effect on news editing, it felt like a renaissance everywhere. Instead of constantly buying expensive chemicals, we quickly learned to work with nature for farming, waste treatment, and even toxic clean-ups. Ma Nature didn't need much help to learn how to eat hydrocarbons other than biological waxes, and it only took a starter vial of bacteria to eat a spill of any size. The microplastics needed a lot of attention, but the microbes have gotten most of it now. Any new technology that looked promising had to figure out how to get into a recycling loop. That did quash quite a few activities, but more often it led to several more new, good, interlocking innovations. The birth of technology had some incredibly harsh lessons and left permanent scars, but nobody wants to go back to what we knew and did before the Industrial Revolution, so there is not much bitterness, and a lot of hope. Our dreams are less glamorous, but much more often realized.
Author's note: no fictional technology was used in this projection. Details are available.