I don't think it's a "what's become of Nintendo" situation; more that third-party devs just didn't see the Wii's success coming. There'll be more half-decent titles coming when they've ad time for a full dev cycle (this coming Christmas, I'd think) but the AAA titles will still hit the 360/PS3 because 1) that's what EA et al had predicted and built their future on, 2) fancy graphics allow them to sell otherwise poor content and the Wii doesn't offer that cover-up, 3) there's this perception of the Wii as a 'family' console - ie it's not marketed at what's been the key demo (mostly guys, 18-30). For me, what this means is opportunity for some new and innovative ways of doing stuff (things like Guitar Hero would suit the Wii really well because of it's accessibility and group gameplay, for instance - yeah I know you don't want ports, it was an example of innovation, stfu); I also think there's a good market for point-and-click adventures and FF-style RPGs on the Wii, neither of which have been hit (I also think a non-hardcore, hour-a-day type MMO could do well). For Big Content, this means ZOMG CHANGE, DO NOT WANT.
On the other hand, now moreso than ever we've variety and competition, which should be good for consumers.
