I'm just gonna reply to this part:
Right or wrong, publishers/developers seem to view the Playstation 3, Xbox 360, and to a lesser extent, PC, as the same userbase, though they particularly target games at the American Xbox 360 audience (which will beat out the N64 in the States before all is said and done). I doubt Activision's really torn up that they only sold over a million copies of World at War on the PS3 versus the 2.75m it did over on the 360. The only ones that are in any danger are those making exclusive PS3 games, and either those publishers are not doing this anymore (Final Fantasy versus XIII is probably the only non-Sony exclusive left outside of much smaller games), or the games are being published by Sony.
It's not so easy to suddenly try to tap into the Wii market. This can be talked about in length, but in short, I think there's a lack of drive for (mainly western) developers to create content for the system, and then there's the fact that they're sort of late to the party anyway. If they got started now, the generation would probably be over by the time they got something out.