I figure the way they have it now, they could really have fun with this.
In the final fight, Revan was portrayed as walking the line... he served the light, but he was corrupted... he wanted to serve the Jedi, but he was falling back into his old tactics that lead him to becoming Darth Revan.
And, from what Darth Malgus said, there are THREE Star Forge-class Rakata installations. The Star Forge, the Foundry, and... one more.
So, let's say sometime down the line, Revan reappears on the Republic side. Amnesiac, memories scattered, fragmented... doesn't remember what happened on the foundry. Pub players start some quests to try and help him out. And...
On the Imperial side, Darth Revan returns... likely during the power vacuum left by the Emperor recovering from the trauma caused by the Jedi Knight, and the death of Malgus and so much of the Dark Council. The Revanites flock to him, and rather than oppose him, Imperial players aid him in gaining recognition and approval within the Empire, as Regent.
Then, at the end of the quest chain, both sides discover the OTHER has a Revan.
And now the mystery begins. Which is the true Revan?
Bioware could have a lot of fun with that I think.
They would have fun with that, but I'd get turned off by the notion of a Phantom Revan or split Revan.