The real question is now, how many years will it take the PS3 to reach the 360's over all sales?
Even then Xbox's heavy hitters seem to sell alot more than Sony's, compare Gears of War to Metal Gear Solid 4 for example. Too Human will probably be a flop. Fable 2 will do MGS4 numbers. Gears of War 2 will a similar rush to Halo 3. We're already seeing the gap fluctuating between the two consoles in weekly sales.
While neither console shows any promise of certainty in their continued trends, its a bit presumptuous to claim the 360 is doomed now given how little a difference big hitting games have made for the PS3 thus far. This can go either way for the Hd consoles and it will be interesting to watch.