1. So you mean do I think Brawl characters will be removed because the newcomers from SSB to SSBM weren't in Brawl but only one game...? Well, then yeah, it's possible and likely they will already get rid of some or even most of the newcomers from Brawl. I definitely know for a fact some will be removed, but definitely not Sonic. That's common sense really. & for characters removed coming back...I'd always hope for a revival of Pichu but more revamped but that isn't likely haha. Everyone seems to think Mewtwo will come back so that wouldn't surprise me, but with limited roster space and time for creating the game he will probably be the only returning character if any...
2. They will probably find some way to merge those into one character? Like when you chose Falco you could change to Fox and have his different yet quite similar moveset. This would keep a lot of characters in and still create new space for more but this probably wouldn't happen, just an unlikely wish... (ToT) But personally, the "cloned" move sets don't really bother me, I still feel like they add some variety in a way...I just wish there was a way they didn't have to rid the game of so many characters each time a new installation comes around. But out of the newcomers of Brawl, Pit is also definitely here to stay, but I practically main him so I guess I'm biased but come'on!
Also though, if Paper Mario is added to the new game, though he is similar franchise wise and looks wise (lols) to Mario, his moveset would be so different, but then he would be taking up the space of the possibility of adding a completely different character from a different series or something...like would you rather have Mario and Paper Mario, or Mario and Rayman? Same goes with Yarn Kirby but I do love that Kirby. I just hope they make some way to incorporate the wishes of people who still would prefer alternate versions of Mario and Kirby into it without taking up roster space, if you know what I mean. I guess some could even argue this goes for Sonic and Shadow in some way, if that makes sense, I can't explain anything well so I apologize for all those left completely confused by my jumbled thoughts & suggestions. ^_^