Banjo's been highly-requested for Smash for over a decade, though, and Sakurai was already interested in him being in. My concern is more on Capcom's side - I recall Sakurai saying in a column or a similar format recently that he went to Square looking for Hero, but would have been willing to compromise and take Slime, if that's what they wanted. My worry is rather that Capcom shoots down Phoenix and proposes Dante as an alternative, if they've got AA on the back-burner. It's not the most likely scenario, but again, I really think it's a 50/50 shot already.
On the flip-side, Capcom's a much more - ahem - amenable company than Square, so they might play ball no matter who he wants.
Oh, I'm not particularly impatient about AA7 itself - I'd like to hear something about it in the next year or two, but I'll live either way. I'm just considering any impacts its absence might have.