We're in 2013. 3 years ago was 2010.
The second largest Video card by AMD, in 2010, was the Radeon HD 5850. Here is a video of a Radeon HD 5850 running FacrCry 3 (December 2012) at 1080p resolution (FPS around 30-60):
http://www.youtube.com/watch?v=vYyt1ByxgSU
So yes... a Radeon HD 7950 will last you 3 years+.
The CPU is something else to look at. In 2010, the middle of the road CPU from Intel was the Core i5 750 (LGA 1156). It actually came out in 2009. That CPU can still power the most demanding of games.
Trust me... good for 3 years