I think, out of the three of them, I can Martha staying on full time again, with the likelyhood of further companions arriving to make the numbers up later on.
I doubt Rose will return full time now, and something tells me even if they wanted her, Catherine Tate wouldn't want to sign onto such a big commitment for more than a year or so.
A lot of people seem to think Martha's popularity leaves something to be desired, but why then, bother to bring her back at all? Surely they'd have approached a companion from the classic series (many of who I'd imagine would jump at the chance to return).
So yes, I think out of the Donna, Rose and Martha, it'll be Martha (if anyone) who'll return full time for the specials and series five, with further companions joining the crew later on.