If this is an inexpensively-produced game, Nintendo would be stupid not to. If they think there's enough demand, I bet they will do it.
Assuming the rumours that Mr. G&W were removed from SSB:B turn out to be false, maybe if you play thousands of online matches using him, they'll get the hint.
And that's assuming it doesn't break some kind of privacy laws for Nintendo to track what characters people like to use most to determine which franchises are popular.