LOL - Love the sarcasm.
Who knows.. Rule of thumb is to get a new card every couple years. The more you invest in one, ie: 300 model vs 150 model, the longer it'll last.
the 7870 should be good at least another year, and the 7950 and 7970 will be longer yet. But how do we know? Were just guessing.
Thankfully we have to thank the consoles to hold back PC games therefore increasing the longevity of the video card. However PC exclusives that required high end cards, nothing we can do about that.