The answer to the question is yes it is is reasonable to assume that at this point. Sure the deluded and idiotic will argue against that. They may even invoke the mythical ten year plan to create a new math to argue the point. Unfortunately for them Sony is in no position to dictate terms to the industry. They are not king anymore. They do not get to work the clock anymore. The generation ends when one of their rivals says it does. Which will probably be Microsoft in the 2010 holiday season.
That said Sony has a little over two years to win this shit, and quite frankly that isn't likely with the divide in place currently. With Microsoft having the lower price point by far. Let alone the fact that Microsoft has negotiated so many former exclusive franchises onto their console as well. Basically the PS3 has fewer advantages to draw upon this generation then any generation before. Not only that, but Microsoft is getting the third party exclusives.
That is far too much to overcome in that small a stretch of time. You have to be realistic about these things. It is actually more likely that Microsoft will trump Sony in Japan then Sony will trump Microsoft in North America.







