Last generation we saw a big playstation franchise jump onto the gamecube , it can happen this generation
RE4? I am not sure if that is what you are talking about, but if it is we should all take a moment to ponder what it means that RE4 is also jumping back over to the PS2. I am sure a few Nintendo execs are still not happy about this, especially since they announced this BEFORE the GCN RE4 launch.
Back on topic... the next gen will be one by developer support and accessibility of the console power by developers. Games already cost a ton to make a years to develop, adding to this problem is going to compound itseld. Whereas AAA titles could be turned out every 2 years in the past by a company, it may take them 3 or 4 now--that is 1 release in the consoles lifetime.
If MS or Sony can allow developers to make high quality games quicker (or at the same pace/cost as now) they will have a leg up. I think that will be Sony's main hurdle. If CELL is uber expensive to make games on and takes a lot of time they are in trouble. If Sony makes top of the line tools that make developing game affordable and take less time then they will do very well. Cost is a big issue next gen, and the developer who is cost effective for developers will have a lot of support.