It's interesting that we had a very similar discussion here minus the actual quantum mechanics. At least intuitively it seems like physical change is what leads to consciousness, not simply the possibility or knowledge of change. One possible counter-argument to consciousness being dependent on decoherence is the following: What if we could choose whether or not, and when, to decohere? For example, what if inside Schroedinger's box is a cat embryo that will be grown into a perfectly normal immortal cat if nucleus A decays, and the box will open if nucleus B decays. When the box opens, is there no cat, a conscious cat, or a cat with no previous consciousness? What if B is extremely unlikely to decay but the cat can press a switch that will open the box? It seems non-intuitive that consciousness should depend on what happens in the future, outside your environment.
I think tying physical change to consciousness is dangerous because that would make things that do not change unconscious or things that stay in a permanent state to lose their consciousness. Indeed we know that atoms are always moving but if we stopped that process would consciousness cease? If I freeze you so you move very slowly does that end the consciousness of your being until things speed up again? How does this work within the mind and soul? How could we stop them and end their consciousness? I don't think you can comprehend consciousness without thinking of it as continuous.
Yet another exceptionally interesting blog post by Scott Aaronson, describing his talk at the Quantum Foundations of a Classical Universe workshop, videos of which should be posted soon. Despite the disclaimer "My talk is for entertainment purposes only; it should not be taken seriously by anyone", it raises several serious and semi-serious points about the nature of conscious experience and related paradoxes, which are generally overlooked by the philosophers, including Eliezer, because they have no relevant CS/QC expertise. For example:
Scott also suggests a model of consciousness which sort-of resolves the issues of cloning, identity and such, by introducing what he calls a "digital abstraction layer" (again, read the blog post to understand what he means by that). Our brains might be lacking such a layer and so be "fundamentally unclonable".
Another interesting observation is that you never actually kill the cat in the Schroedinger's cat experiment, for a reasonable definition of "kill".
There are several more mind-blowing insights in this "entertainment purposes" post/talk, related to the existence of p-zombies, consciousness of Boltzmann brains, the observed large-scale structure of the Universe and the "reality" of Tegmark IV.
I certainly got the humbling experience that Scott is the level above mine, and I would like to know if other people did, too.
Finally, the standard bright dilettante caveat applies: if you think up a quick objection to what an expert in the area argues, and you yourself are not such an expert, the odds are extremely heavy that this objection is either silly or has been considered and addressed by the expert already.