I'm going to go out on a limb and say that it will be the decedent of Bastila. As for it being the child decedent of Bastila and Reven they might leave us in the dark and let our imagination wonder.
Bastila being alive could be either she left the Order and was not considered a threat by the Sith but thats hard to believe since she will be well known for her battle meditation abilities. Active Jedi or not she would be a threat to the Sith. I believe she was suppose to die on Katarr but for some reason she never made it or ended up involved in another issue. I would think that Bastila's ability would make her a target to the Sith and so she would either have to fake her death or the Sith believed she died on Katarr.
I wonder since we saw Bastila on Telos IV which is a wounded planet....was Bastila there the whole time? Where was she hiding? or was it with Carth's flag ship she was hiding on?
So many questions...........