I can agree with most of this post but you're ignoring Blue Dragon, Mass Effect, Trusty Bell, and Lost Odyssey for the 360. All RPGs, all from established developers, all AAA games that will move consoles (some to a much greater extent than others).
Also, MGS will be a big system-seller for the PS3. It's the type of game that people clamor over when a console moves to the next generation. It will look beautiful and sell units, no matter whether it's good or not (it probably will be good, if not great). MGS was huge for the PS1, MGS2 was huge for the PS2, MGS4 will be huge for the PS3. Unless Konami goes multi-platform. Then it's wide open.
I have my doubts about Blue Dragon, Mass Effect and the others because they aren't reputable franchises, and no one can be certain for sure that they will indeed move hardware. High sales? Of course. Attached hardware? Doubtful. If you base your facts on established developers, and that they are AAA games, then the same can be said about the PS3, but again, doubtful.
I don't think the MGS franchise was in a position where a console relied on them to really boost sales. Again, just by looking at the fact that sales are higher in the U.S., MGS 4 will move hardware in the U.S. Don't know about Europe or Japan.