Sakurai has said the pool for potential newcomers has thinned. Mario characters are always a safe bet as they appeal to everyone, while typically having a consistent demand.
I think Sakurai should open his peepers a bit wider. The pool has thinned, but it's not that bad. I can name ten small franchises who could have a character, and ten characters from existing franchises.
Either way, the way he makes it sound, I could see Krystal getting in because he feels there is a lack of characters, when both her, and Toad could wait a round.
Still my ultimate roster guess is this: Zoroark, Deoxys, Mewtwo, Samurai Goroh, Ridley, Dixie Kong, King K. Rool, Palutena, Medusa, Little Mac, Issac, Shulk, Chrome, Roy, Young Link, Krystal, Toad, Bowser Jr.
Some of them have specific reasons behind them. I'm thinking about adding Saki...but I'm not too sure.