Well, I'm a GTX 460 SLI owner.
It could last few years, it only depends how picky you're.
With 2600k + SLI GTX 460
I CAN'T (all with 1680x1050):
Max Metro 2033 (with or without 3D Vision)
Batman Arkham City DX11 with Physx max (with 3D Vision)
Witcher 2 with ubersampling. (with or without 3D Vision)
There's some games that I can't max already, hard to tell the games to come.
If you not that picky, yes, it will last couple years