I have been wanting Sami in for a good while, and I think that she is the only AW character who could really represent the series.
I still hold out hope that Zelda transforms into uncursed Midna instead of Sheik while retaining all of the latter's moves and style. I think it could work.
As far as Ike is concerned, after sleeping on his announcement and doing some research on him (I have not played Radience), I have a feeling that he may not use the Marth/Roy move set. Aether may also be his FSA, and it may be completely separate from the mentioned one-hit kill move; the wording can be taken either way really.
I have also reevaluated my belief that he will replace Roy, I still believe that Roy's chances of staying in SSBB sunk pretty low after Ike's announcement, but I still fill he has an so-so chance of staying in (around 30 - 35%). Marth will in all probability stay in, but part of me thinks that if Ike does have the Marth/Roy move set, and given Sakurai's comments on trying to shy away from Japanese only characters (although this statement does not say he will not put in any new Japanese characters, it merely stated he would like to avoid it, not exactly a strong statement against the inclusion of a Japanese only character), Marth may find his own chances of returning getting worse.
Of course this is all just conjecture.