I think that it's pretty foolish to come out and say that the people who are badmouthing the WiiU are going to go out and buy it. I think that there will be quite a few who do go out and buy it after they've dismissed it, but I imagine the majority won't.
Personally, I think that Nintendo have been very savvy with this new system. They created the Wii to draw in the 'casual' crowd, which they managed extremely well. The way I see it, they're banking on a large number of that market buying the WiiU because they liked the Wii, but Nintendo are also marketing the WiiU to 'hardcore' players as well, who they're trying to draw in with improved hardware and third-party support.
EDIT: Having said that, I'm not sure that Nintendo will actually draw the 'hardcore' crowd back in, they may have burned their bridges there. Couple that with the fact that the WiiU will not be next-gen, and the rumouurs about new Sony and Microsoft systems may be enough to damage potential WiiU sales.