(Arthur C) Clarke's First Law: "When a distinguished but elderly scientist states that something is possible, he is almost certainly right; when he states that something is impossible, he is probably wrong."
... has turned out to be correct often enough that I wouldn't want to place large bets on this.
(Digression: there's an obvious difficulty in assessing Clarke's First Law. When someone says something is impossible and is wrong, we can tell because, lo, someone else does it. But when someone says something is impossible and is right, we'll never really know for sure; the most we can say is that no one has done it yet. So: time travel? teleportation? faster than light travel? Plenty of eminent (and in some cases elderly) scientists have said, and doubtless will continue to say, that these things are impossible; for all we know they really are; but even if they are we'll never know for sure that Clarke's First Law is wrong for them.)
[EDITED in response to two comments: If the claim is "3D done just like it is now will never work" then I agree that CFL isn't very relevant. If it's "3D movies will never work", which is what I think "3D doesn't work and never will" ought to mean, then I think CFL applies. So maybe I'm really only criticizing Ebert and not Murch, who does embed into his comments the sentence 'Nothing will fix it short of producing true "holographic" images.'. I do wonder whether the quotes around "holographic" are trying to define it to mean "anything that fixes this problem" rather than strictly "something close to full-wavefront reconstruction using coherent light", in which case I guess he's right by definition and therefore vacuously. I would certainly not want to bet that actual literal holograms are the only way to solve the problem.]