The way I see it, when he disappeared, everything he was wearing also disappeared. In particular, his signature mask disappeared with him. I figure since his mask (and robes, although they're less symbolic) wasn't left behind, he's probably alive. If not, he'll likely return as a force ghost.
Love how Meetra's ghost has my favorite lightsaber hilt, being such a minor Revan fan or imposer ( sarcasum on the minor. ) Is there a reason they decided to have him use Purple saber when they originally had him using Green like in the Book? I found a screenshot on google images showing him holding a Green lightsaber, with hood up-mask on. Then you look at him now, its Hood disappeared, mask on....very confusing.
I don't know about the purple saber, maybe it's symbolic of his balance between the light side and dark side.
I believe that in 1.2, they made it so certain masks could be worn under hoods. Both Darth Marr and Revan regained their hoods over their masks.