I think he's a new character. It would be the most interesting option to me. I've said it before, I'll say it again - why would I want to see a story I've seen before retold with different actors? Why would they go to the trouble of rebooting an entire universe to retell a story that's already been told?
Bringing back a character doesn't mean retelling the same story that featured him. The Wrath of Khan
was a completely different story from "Space Seed." The 2009 movie had Pike, but it was completely unlike "The Cage." It also had Sarek and Amanda but was completely unlike "Journey to Babel" (though parts of it were very close to scenes from "Yesteryear").