I suppose I am referring to their prominence and their likelihood. So both.
I mean, it is blatantly overt that Mario and Zelda are Nintendo's most influential series; and thus, I believe it is rational to assert that it is entirely likely that we may see another Mario newcomer and an additional Zelda newcomer. Precedent dictates that we may be seeing another Zelda representative and intent might allude to another Mario representative. Toon Zelda and Toon Sheik were both planned for Brawl, as such, it is likely that we may be seeing, at the very least, one other Zelda character. Mario, this is a franchise I am not entirely sure about. As of current, we have just as many Mario characters as the installment prior to Brawl. So an extra representative seems obvious; however, as noted, we do not really have a lot of space left in the roster. So I am not sure if another Fire Emblem character would take priority. Again, one must account for the premise that intent tends to change over 5 years. So your guess is as good as mine.