I say we all cool our heels and wait to see what happens. It's far too early to make any kind of assumptions right now. The talk of clones is rubbish and an excuse for people to bash on a character they don't like. If we go by how things went from Melee to Brawl, we can assume any cuts made would be based on advertising.
Shall we talk examples? Let's go with Donkey Kong. Chronobound had it right in a lot of ways in his analysis, and with the new Tropical Freeze adding in Dixie and a fourth unknown, possibilities are strong for Dixie and K.Rool making appearances, reflecting the new change.
For the other end of things, Pokemon and Fire Emblem have already seen a similar roster change of trading in for the newer generations.
As far as Young Link and Dr. Mario goes, Y.Link was traded out for the representative of the hand-helds, and Dr. Mario was only scrapped to make room for what they felt was a bigger opportunity in Sonic, if I'm reading it right. Again, mostly business decisions more than anything.
Either way, the point remains, assumptions aren't going to get us anywhere. There's no solid proof yet to know where things are going, only what we know from the previous roster change. Until we see what happens with the more unpredictable franchises in here, just cool it with the bashing. We're all hyped up and it's not good for rational thinking.
That said, I don't think we're going to see a decrease in the roster size, but not a big increase either, since that doesn't seem to be his focus right now. Depends on how much room he has to play with after he's done working with the game mechanics he wants to try, I suppose.