I'm wary of comparing sales of PS2 games to GameCube, however, and usually would prefer to compare GameCube to Xbox which had very close overall sales numbers (with the Xbox leading by a mere couple million). In that scenario, the Xbox still maintained better sales and support where 3rd party companies are concerned.
The Wii reaching 85 million should've been healthy for 3rd party devs but it still wasn't, except in rare cases. Hit franchises still struggled on the system. The casual audience doesn't seem to know a quality gaming experience from a throw-away iPhone app, so they didn't know to support, or expand to, what some of us would consider hardcore or "real" 3rd party video games. And the Nintendo fans... as is typical, pretty much just bought Nintendo stuff.
I do see how Cafe, with it's power roughly in line with PS3 and Xbox360 could manage some better ports of 3rd party games--like Call of Duty not being downgraded in any way, but I both see the support as slow to catch on, and quick to move away when the next Xbox and Playstation launch.
I firmly believe there are still treasures to be found in the Xbox360 and PS3's respective hardware, but I'm not kidding myself--while I love that this generation has legs (and it should), the limits of both systems will become far more apparent within the next two years. When Sony and Microsoft launch their next consoles, those limits will be left behind--except in Project Cafe--which will then be, last-gen tech.
Okay for the top part. For the last paragraph, again, time will tell. There is lots for us to learn still, but just logically I think it very unprobable that Nintendo would launch a platform that would be considered last gen for another 4 years, given their aggresive new stance on attracting the core.