Dark matter -- accepting completely that it does exist in reality -- has no option than to be of universal material from the initial supposed explosion, from any existing planets and from supernovae since forever, with the ejected material not combined into new stars being expelled into galactic and inter-galactic space and remaining invisible.
Which origin it is can be ascertained by looking at the composition of 'present' stars, either by inspecting galaxies and estimating in a general sense the level of contents of their composition, if that is yet possible, or by scrutinising those of the stars of our local galaxy. Our local galaxy alone is said to contain 1 or 200 thousand million stars, apart from those which have already exploded as supernovae, and there are said to be at least the same number of other galaxies, so there is much inter-galactic debris.
It happens like this --
A typical cloud of gas in space moves at a speed of a yard or two per second, but when it contracts, like a spinning skater's arms drawing in, it spins faster. As it approaches its star-size, it is spinning so fast that centrifugal force automatically causes up to twenty percent of its mass to spin off in its equatorial plane. This slows and stabilises the rest of the mass and the expelled material can form a planetary disk which, in time, can form planets.. However, more massive stars spin off even more than twenty percent, thus stabilising the rest of their mass. These stars, seen to be of blue colour due to their higher temperatures, last no more than fifty million years before their high rate of fusing their fuel causes them to explode as supernovae..
Matter cannot be simply annihilated; it can be converted by fusion or fission, or merely fragmented, but not eliminated. So once in existence, it remains so, and the long history of star formation and equatorial ejection, means that there is an abundance of material permanently in existence. Quite apart from all the 'present' planets, which are not illuminated as stars, there is all the fragmented planets and eroded material of the evidently-many past supernovae, black holes and other more exotic forms of unilluminated matter.
This means that much more debris can be expected to have originated from supernovae than the minor mass of 'present' planetary material would indicate as evident from the trivial mass of planetary material compared to the host stars' mass.
The proportion of stars with a higher level of complex atomic particles indicates the proportion of past supernovae compared with the number of existing stars. Material from supernovae not included in present stars will exist in intergalactic space, of which there is abundance, and will not be illuminated. Therefore it is 'dark'. How much space there is can be judged from the fact that M31, our neighbouring galaxy, is at a distance of about 2.5 million light years, and now is much as "Lucy" back 'then' might have seen it.According to Hoyle (Sir Fred, in this case, not Edmond), extra-galactjc matter has been there long enough for atoms and molecules to combine to form biochemical materials, too. the most common being cellulose.
Whether stars of 'the future' as seen from our position in space can contribute to stars seen from our 'present' position is not certain, but the possibility might be considered.
Some years ago there was an article called 'Size Matters', which dealt with matters of the size of Universe, but here we are dealing only with percentages ('dark' said to be more than 95% of all universal matter), so universal size as such is not relevant.
So perhaps in what is considered from here as the very dim and, if not very distant, 'future', so long, of course, as Fred's Steady State theory is not correct, a last cloud of hydrogen's resultant star will routinely explode in its own sweet way, and then . . . 100%! The process of Universe is complete.
Look back from there, however, and you will physically see all 'the past' as we see it now, as 'time' exists only depending from where Universe is seen by living creatures with the sense of 'time', all Universe in reality existing simultaneously, but visible to us only as what has already happened and as in motion.
Enquiry is just the result of a mental itch, and its answers are just as irrelevant. But the 'past' as seen from here, still exists, so all's well with Universe.