The interesting thing about this entire scenario is how many Nintendo fans are pushing for boycotts and throwing firebombs at Ubisoft--the third-party publisher that has probably shown the most support for Nintendo. Smart, that.
So what happens if every single Wii U owner only buys a used copy of Rayman Legends (hah)? What's the goal with that? Is it to push Ubisoft off the Nintendo platform? Yeah, they certainly deserve that, what with developing a Wii U launch title and everything. Is it to get Ubisoft thinking, "hey, you know, we did the right thing, the Rayman Wii U numbers are horrible," so that they can feel justified in their decision? How very charitable.
I think some people need to take a step back and rethink this. You have to wait a few more months, so what? It's not like the game is going to magically get worse. If you wanted to play it now then you should still want to play it later. Anyone out there boycotting Pikmin for their delay? No? If you can survive that, you can survive this.
I remember a lot of people saying, "a real fan would buy a Wii U to play Bayonetta 2". A real fan can't wait a few extra months? Seriously?
Really, though, go ahead with the plan to convince third-party publishers to stay away from the Wii U. Give them negative numbers they can look at. That way you can feel a rush of triumph when Ubisoft skips over the Wii U development entirely.