A lot of games do support higher resolutions, but at a performance cost, and 1080p will be standard for at least another 3-4 years.
Gaming on a TV is not ideal either, a monitor would be more suitable; if your TV does not have a game mode it may have bad input lag and ruin your whole experience.
By the time you need a new graphics card you can get something higher resolution.
Basically, 1080p is fine, get your computer, and enjoy! - Just check your TV first, it is simply not good to play games on modern TV's with all these processing effects, it's horrible.