Gootecks relayed this Twit Pic from @marika_j. The Japanese SSF4 arcade release indicates two new fighters are inbound. The common held expectation is that they will be DLC not too far in the future for us on Team NAH.
Gootecks predicts one to be an Alpha fighter, and also that Urien will not be included.
I am rooting for Charlie (from Alpha), as I have mentioned repeatedly in this space. Guile is so revamped now, I think a clone version would be warranted. My pick for the other slot is Alex (from SF3). There are already, you know, plenty of grapplers, but, like Abel, he has a diverse arsenal. Although, and I'm speaking without any specific knowledge, I don't know how the SF4 engine would handle his back-turned shenanigans.
Otherwise, my guesses would include Rainbow Mika, Yun, and possibly another Final Fight character, even possibly one that has never appeared in a SF game... namely Mayor Mike Haggar, who is rumored to be in MvC3. You know, Poison would be cool too, actually.