The only problem with this prediction is that the legs could get cut off by something like The Conduit. Possibly not due to the fact that WWII settings are more popular than sci-fi settings.
@Esa-Petteri: It's not about total sales, it's about sales growth. The 360 version is declining where the Wii version is growing. It won't be an evergreen title like Mario Kart, but it should grow legs to keep it going till a superior FPS steals it's thunder.
A game I'm developing with some friends:
www.xnagg.com/zombieasteroids/publish.htm
It is largely a technical exercise but feedback is appreciated.