Well, you can't prove something that hasn't happened yet. So proof is non existent.This theory has been disproven on nearly every page of this thread.
Facts such as no hardcore Wii games are selling, which shows who the Wii is selling to, the global sales of the 360 and Wii are nearly the same, far more 360 games are selling than Wii games, the fact that only 1/3 of 360 owners have Halo 3 (5 million in two weeks is still record breaking, before you decide to use that as an argument) regardless of the massive hype... Hype Brawl can't possibly match.
There has been plenty of evidence of what's to come however, from both sides. But neither of the sides of evidence debunk each other yet.