If this game were being developed by Next Level Games I'd say Kritter would be a shoe in for goalie duties, but it's hard to say at the moment.
And I have often thought since Nintendo own Krunch from Diddy Kong Racing(the other characters aside from Diddy belong to Rareware) they should use him in these kind of games.
Overall it really would be nice to see a few more of the Donkey Kong series characters show up in these Mario spin-off games. I'm really surprised Dixie and Cranky especially don't make more appearances considering how important they are to the DKC series history.
My predictions for this game's roster:
We've seen most of it already. We might get a few more characters like Nabbit, Drybones, or Toadette, but what we've seen so far is pretty much it.
I say this because Camelot's games usually tap out at around 16-20 playable characters and we're already at that, so I'm not anticipating much more than this.