
None of that stuff is being done on a single computer.....they use render farms with the best cooling systems possible. I'm not saying we won't see any big advancements but its going to take alot more than computers becoming more powerful.
They would have to find a way to put 10 - 15 powerful computers into 1 for your average consumer.
EDIT: Also none of the stuff in the movies are interactive, meaning less calculations than video games have to do( I do game programming as a hobby ). Theres a ton of calculations that go into the littliest stuff ( angle/speed/collision detection, what to do after objects collide ). This is part of the reason why trailers look better than the actual gameplay.