I asked Hall Hood directly via the twitter in an attempt to get some hint about Revan's potential future fate. Here is the response that I received:
@hallhood Kudos to the entire BioWare team for Makeb - simply amazing. I hope we can expect more story content soon (Revan's return perhaps?
@LoreFreak1 Hehe... we'll see! Glad you enjoyed Makeb!
Interpret it as you wish, but he did not say no.
As I said numerous times: mark my words, we will see more of Revan yet (would have been better to get brand new single player RPG game, but that is so not going to happen).