I think vaanrose is right in that we're going to get a lot of clones, but I'm personally feeling 3 more newcomers and 4 more clones with the possibility of 2 newcomers and 5 clones.
If I had to wager...
3 newcomers:
K Rool, Simon (if vergeben is true. If not, replace with Geno or Rayman), and Chorus men.
Likely clone candidates include Dixie, Impa, Dark Samus, Chrom, etc.
(I would LOVE a dry bowser with melee/brawl bowser moveset, but I don't expect it)
I'm not expecting it anymore after I sat down and thought about the remaining newcomers as well as returning pichu/pokemon trainer.
We've got Decidueye, who is probably way less likely with the return of ivysaur and 5 other archers (2 pits and 3 links, not even counting final smashes).
We've got Mimikyu, but we already have pichu who looks similar to pikachu, so would having a 3rd pikachu lookalike be really appealing?
And there's lycanroc, who competes with duck hunt dog, wolf, and lucario in the dog-like characters.