It's really hard to say unless you're an EE at a major TV company...
All I can tell you is that there are 3 technologies I know of coming out - TV can only get so clear before no one notices the difference!
1) 3 angle TV - This tv has 3 tuners built in, along with different viewing angles using colored lasers. 3 different people can be sitting in one room, one in front of the TV and the other 2 on each side at a 45 degree angle and all watch different shows at the same time, on the same TV!! They'll have to use cordless headphones for the other viewing spots though...
2) HD2TV - a European company has perfected a technology that is 25X the resolution of HDTV!!! They have designed the camera's, media, and players. At this phase, they will only be releasing it to large theaters with a big budget, however it is backward compatible with HDTV so you can then buy the movie in HD or Blu-Ray
3) My favorite :) 3D TV!! The video will be recorded from 16 angles throughout the movie, then "interlaced". If you were to play this content on a regular TV it would show as a blur, however a special 3D TV will have a lenticular lens over it making the image appear as if it were sticking a few feet out of the TV!!! Tell me you would buy that?!
From what I've heard, these are the next generation TV's, but I haven't heard of anything just going up a little in resolution...
Hope this helps!
...to clarify for the person asking about the difference in 1080i/p:
"i" stands for interlaced meaning lines 1/2, 3/4, 5/6 etc are showing the same frame at the same time...
"p" stands for progressive meaning lines 1,3,5,7... are playing a particular frame while lines 2,4,6,8... are playing the next frame to make the video more "fluid" or lifelike, however you are not gaining any resolution, this shouldn't dissapoint you - it is a better picture, you just aren't gaining resolution.