I think if we use traditional modeling, it would be over the hill, starting its downward decline. However, none of the current-gen systems are using the "traditional" model. Microsoft, with Natal, is trying to put a second hill in the path of the 360 for it to go up again. Sony seems to be experimenting with speed in going up and downhill, looking at the long-term picture. And Nintendo seems to just be building a new hill in general, and now they're using a bulldozer to push more dirt up to the side, creating a plateau like they did with the DS. If everyone gets their way, nobody has truely "peaked" yet, including Microsoft. If things go awry (in MS's case, the ball rolls the wrong way down the hill), then things may end much sooner than anyone wants.
-dunno001
-On a quest for the truly perfect game; I don't think it exists...