Don't ask him.
When it comes to the future of Jeffrey Dean Morgan's character, clearly we can't count anything out - but he's as clueless as we are. From E! Online's spoiler chat today:
Q: I can't wait to see Jeffrey Dean Morgan in Watchmen! Will Grey's Anatomy fans like his character in the new movie?
A: Actually, no. Jeffrey says that the Grey's Anatomy fans will be shocked by his Watchmen character, Comedian. He's very unsavory! On coming back to Grey's Anatomy, Morgan says:
"I really don't know. They keep me out of the loop because I'm a talker. They're real careful not to tell me anything. When I was lucky enough to go back there, it was just a thrill to go back."