France may have done more to recognize the Islamic State than anything ISIS has done so far. In declaring the Paris strikes an act of war, France has de facto recognized the Islamic State, and already begun backing that up with targeted air strikes against its "capitol" Raqqa.
Now, it may invoke NATO's Article 5, which would require other NATO members to commit to defending fellow NATO member France against the Islamic State. Lost in all this is whether the IS carved out of Syria, Iraq and possibly other countries at least aspirationally, will acquiesce and treat NATO attacks as attacks against ISIS, or against them. This may be the beginning of WWIII.