I think a lot of you put a lot of stock in the "has strong ties with Nintendo" or "has a good history with Nintendo" when characters like Cloud and Joker have shown that that doesn't mean squat. I remember hearing the whole "Rayman is very likely because of how close Ubisoft has been with Nintendo". Yeah, so much for that theory. I don't think Sakurai cares at all if a 3rd party has or had a close relationship with Nintendo. Maybe a little. But it doesn't seem to be a priority.
So if Banjo-Kazooie is chosen it will be because of how highly requested they were.
To be fair a lot of us didn't say BK would get in solely or because of Nintendo history, we just say that it plays a factor, gives an edge or couldn't hurt to have it and unlike most 3rd Party's he didn't just appear on a Nintendo console, He was owned by Nintendo at one point, But you are right that fan request would probably be the main factor.
No offense ,But I always groan when someone says "Why is Cloud in ? He doesn't have Nintendo history or never appeared on Nintendo consoles". I don't know crap or care about Final Fantasy, But the franchise had history with Nintendo before Sony came along with the Playstation, They just decided to go with the most popular character from the franchise's biggest game that just so happen to be only be available on the PS1, Bottom Line: He's representing the Final Fantasy franchise as a whole and Square Enix (3rd Party) Not Sony (1st Party).
That would almost be like if Raiden from Metal Gear Rising got in Smash Bros instead of Snake, He never appeared on Nintendo consoles as his game was on PS3 and Xbox 360 ,It would be a really weird and controversial choice ,But he would still be representing the Metar Gear franchise and Konami as a whole.
I don't know jack about Persona either ,But I've heard that it's a spinoff or has ties to another series that has has previous history on Nintendo consoles too.
Rayman still has a solid chance as DLC, His faith hasn't been sealed yet, Though I don't feel as confident about his chances as much as I did before.