Interesting but overly melodramatic; the non-existance of "free will" in the traditional sense would seem to be beyond reasonable doubt already, but that hasn't stopped 99.9% of the population believing in it. I don't think anyone is going to be devastated simply because there is not going to be a magic event that suddenly convinces everyone that their sense of control is illusionary. Furthermore the melancholy tone of your prophecy misses something key: That what we consider important is essential up to us. You have (IMO rather bizzarly) decided that "creation" (whatever that means) is important, but the great loss of "meaning" is nicely eliminated by relegation of "meaning" from something desperately important to something totally irrelevent. The quest for knowledge, understanding, experiencing the wonder of the universe, of life, indeed the very substance of living stands untouched by revelations about our internal workings.
my vision of the future involves no imposition of structure among the people, just a future where people have found evidence of the deterministic nature of the universe. as a result, everybody who thinks about the issues of life will come to realize how meaningless it is - and it will not be conjecture, it will be fact. some will rationalize it with bizarre religious logic, others will do their best to ignore it, observing that people lived just fine in the past without letting this worry them, and for others it will devastate them - they know that creation is the only worthwhile thing to live for, and will also know that their creation is false. it's a matter of how many will fall into each catagory