The most likely theory I've seen is that Nintendo likes to end on a recent character (I know Corrin was revealed before Bayo but they released at the same time so I'd argue that it definitely fits) so that the game ages a bit better in the long run. Honestly, if they go with this again, I think gen 8 is a bit too old (as is Ring Fit) so I think they'd probably have to go with Nahobino.
I just hope we get something, at least a Spirit Event, but I'm hoping for a Phoenix Mii Costume (dream is with a track, but they haven't done that for a while). Because if we do get a Capcom character, I can't see them adding Ace Attorney before Devil May Cry, Monster Hunter or Resident Evil.
I've heard this theory yeah, not a bad idea, and while I'd agree, I was saying that about Incineroar, Gen 7 was on its way out. I didn't believe the uh pwshh "Grinch" stuff, but I didn't believe Incineroar was coming either, I thought it was too late, he missed his chance. But he popped up anyway, and if they skip my favorite fire bunny now, then wow, I just don't get it I guess haha
And yeah,
I mean, I'd argue that Mega Man was way less relevant in 2013 than Street Fighter and all the other series' you mentioned were. Same goes for Banjo being the first Microsoft rep over Steve, Master Chief, etc. While relative popularity definitely matters, I don't think it's prioritized over moveset potential.
It's hard to say, but yeah, weirder things have happened? Banjo had a thing with Nintendo (and just fan demand, but the history definitely helps) so got in over more iconic Microsoft characters, but also Snake got in over the Castlevania boys partly cause Kojima and friendship... Popularity helps, connection with Nintendo helps, personal favors help?
Megaman and Ryu are already in, Monster Hunter devs have shared they think the best representation is through the Monsters which we have with a Rathalos boss fight...
Resident Evil is possible, I personally feel like their tone doesn't fit, and things like Nemesis seem too disturbing to even show up as a spirit, but MvC2 Jill is cool and something like that could work...
Dante's also really possible, and while Kamiya did put up that poll a while ago about which of his characters people'd wanna see in Smash and Dante won before he took it down, he's also shown interest for Wright in Smash? To be honest I'm not sure what this one means,
https://twitter.com/PG_kamiya/status/1075222957507502080 someone basically said "I loved seeing Bayonetta of Platinum Games get in, I'd also love to see Phoenix Wright from Ace Attorney to get in Smash as DLC" and he retweeted it and I guess, according to google translate, said "'Platinum Games' is not it..." like... Saying that Bayo isn't from Platinum or...? There was also this time though where he shared while drinking with Takumi that Takumi was wondering why Wright wasn't in Smash
https://twitter.com/PushDustIn/status/1201290146580070400?s=20
It's naive of me, but I think it'd be really heartwarming if Kamiya saw he already got Bayo in and did his buddy a solid and vouched for Wright maybe? No clue, not even sure if Kamiya or Takumi or Sakurai would be in initial negotiations, not sure who the Nintendo folks deciding DLC would go to at Capcom or wherever...
But I guess my point is, nah, Phoenix
could totally get in first over Monster Hunter, Resident Evil, or Dante. He's got the tighter connection with Nintendo, more unique potential (though I'm sure Dante, RE, and Monster Hunter, despite their swords, guns, bows or other weapons could also be plenty unique), and possible friendships to help. No guarantee, but enough of a possibility for me to get my hopes up ha!