Well, very high resolutions are useful in a home setting, but only if you're sitting two feet from the screen (as with a computer monitor) and you want the individual pixels to be very small.

Otherwise, with home theater, 1080p is more than sufficient (especially if you're upgrading from standard definition). With digital mastering, each frame of a movie would look basically smooth to you, even on an extremely large display. So, overall, I'm guessing 1080p will be the standard for quite some time to come.