That is EXACTLY what I foresee if they boycott it. If anything, it'll show Ubisoft that they made the right choice by making it multiplatform.I would additionally like to point out that most of these boycotters are disgruntled Wii U owners. I don't see many non-Wii U owners complaining about this and vowing to boycott it. So in the end you're not just hurting game sales, you're hurting game sales for the Wii U. If Ubisoft sees the Wii U as a market not worth developing for because no one bought their game on it, they just won't develop for it.
So the end result is either A) the boycott is so insignificant it does nothing, B) the boycott is large enough to ruin all chances for a sequel, or C) the boycott is big enough on the Wii U that Ubisoft won't develop for the Wii U anymore.
Sounds like great options.