AFAIK Comet has not been confirmed
I don't have much more to say about it. Ubi has not confirmed it, so I think it's a little premature to have a forum for it.
I don't see the harm in it. Didn't we have a forum for "Assassin's Creed 3" years before it was announced? If Comet was a working title, the info leaked was false, or a second AC game is not actually coming this year, it's not like it would be difficult to change the name and description or delete it and send these topics to Black Flag or Unity.
However remember that this leak came from the same source as the person who leaked Unity, and they were correct there. I think that gives it some credence, as does Unity being confirmed for Next-Gen only.
Also: http://attackofthefanboy.com/news/ubisoft-connectivity-supporting-gen/
“We will have games for PS3 and 360 for this year and probably the years after. We want to be able to provide games to people who are playing on these consoles."
Pretty safe to assume that Comet or a game fitting into the same "last gen exclusive" role is going to be announced.