It'll definitely help, and it's a good start, but Mario isn't going to do it alone this time. If we're lucky, the Wii U will surpass what the Gamecube was around the same time frame - and that's a big change; a good change.
It's going to be a combination of Zelda, which is already doing its job, Mario which seems to be picking up a lot of buzz and a few other titles that people have probably written off as system sellers. Wii Sports Club will do good things for the system, but they should really bundle it along with Nintendoland or Super Mario 3D Land this holiday. Also, Wii Fit U should move quite a few units. Especially because it's free if you already own the first one. But again, Nintendo need to market that. How are John & Sue Person, who use Wii Fit daily, going to know that, that bundle or promotion exists?
So yeah, Mario and the combination of the rest of the upcoming titles will help. Don't expect Wii levels of hype, but a good amount of buzz this holiday and probably moving enough units to surpass the Gamecube. It's basically a re-launch.