I think they still can play current games with lower settings. For example cards like GTX 260 or GTX 285 can still play all the current games with good details enabled. Obviously for demanding games, you've to lower the details for fluent game play.
So going with HD 6950 2 GB version is a wise decesion. Most of the current games don't use more than 1 GB Video memory at 1920X1080 or Full HD resolution. But it is noticed that Battlefield 3, the upcoming title is using more than 1GB VRam. So 2GB version is futureproof and I think you can go with for 2 Years without any issues and even after then you can play all the games with lowered details.