2010 shrink the die size
2011 new architecture
2012 shrink the die size
Nvidia and Intel are both going to put out really high performance chips on the new architecture before the die shrink, but I am not going to buy them so it's irrelevant. An i5-2500 + GTX 560 are a great price / performance match and things are not going to really change much for another year.
For how long? I paid $500 or so for my Radeon HD 4870x2 around 2 years ago, and it's done everything you described since then. In my experience, getting high end video cards is a better choice in the long run.