CUTS
Surprising lax here compared to other people's list. But I do believe this will be a sequel akin to Splatoon 2/Xilla 2. Mostly recycling a bunch of assets while adding a bunch of new content. Personally I'm hoping there's no cuts but If I had to guess on them..(assuming the Switch doesn't get a time consuming story mode being developed like SSE)
MII FIGHTERS- They just didn't work. Custom Moves while a cool idea, just didn't work out in SSB4. They could revamp them for this game which makes this reason I think they will be cut not substantial. The main reason is that the Miis seem to be downplayed/phasing out. From what I heard the most prominent role Miis have in the Swith Era is in Mario Kart 8 Deluxe, a Wii U port.
CLOUD- He was a very fun character to play, despite being aggravating to fight. 3rd parties in general are at a higher risk at being at cut in general. We have 6 in SSB4 so I have a feeling not all of them will return(and Guest characters in general tend to be one term only in other fighting games), and the one I think is the likiest cut out of everyone is obviously Cloud. There's no greater evidence here than the general Final Fantasy content in the game. It's very lacking. The only trophies are just Cloud and his alts(while Ryu gets Ken, and Bayonetta gets Jeanne, Cereza, and Rodin). And the fact there's only two songs from it. Cloud definitely seemed much more difficult to get the rights for compared to the other 5.
On the Pro side he's easier to get compared to anyone from Konami(RIP Snake) or........ Disney(Sora is not happening with this copyright crazy company owning him)
RETURNING VETS
ICE CLIMBERS- No Duh. They were intended to be in the game but couldn't because the 3DS couldn't handle 8 of them and possibly 8 player Smash on the Wii U version. There pretty much a lock...... unless 8 Player smash still can't handle them.
WOLF- Highly wanted to come back. He didn't for some reason. I'm guessing because in general Mewtwo, Lucas, and Roy were much more requested compared to him as mentioned in the interview. And of course the DLC wanted to focus on new characters for DLC. Less likely to come back compared to Ice Climbers but still has a great shot.
NEWCOMERS
King K. Rool- Still a highly requested character, and even was acknowledge with that distinctive Mii Costume. Also a want of mine.
Zelda Newcomer- I don't know who, but I find likely there will be someone new(going with Impa or Classic Ganon since they appeared more than once in a mainline game).
Ridley- Like King K. Rool, Very requested and his time might shine now.
Takamaru- The most likely retro rep. He was considered for SSB4 but because his game wasn't localized, he was scraped. Now now that his game is out globally that obstacle is now crossed.
Gen 7/8 Pokemon- Each Smash game has had a Pokemon newcomer from the latest gen before Smash is released. I'm leaning on Gen 7, but possibly gen 8 if it's revealed around E3 and was developed before the roster for Smash Switch was finalized.
Rex & Pyra- Probably the safest bet here. Xenoblade is growing in popularity and there's no doubt the game started development before the Smash Switch Roster was finalized.
Rhythm Heaven Character- There was an icon discovered from datamining, so it's one of the new IPs that will be added IMO.
Dillon- Another possible new IP. And there's a new game out right now. He was an assist trophy and we seen them become playable.
Inklings- Confirmed
Lloyd Irving- Oh boy I'm probably going to get stoned here(at least I didn't put Goku). My most wanted newcomer and my pick for 2nd rep from Namco. He was added as a DLC Mii Costume. The Tales Series is still the 3rd most popular RPG series and it's growing more popular globally too(Tales of Links and Tales of The Ray mobile games were localized).
Ryu Hayabusa/Kasumi- Koei Tecmo has a pretty good relationship with Nintendo so I wouldn't be surprised if they had a rep added.
67 Character Roster