So far, we only know one thing for sure: FCP X is the successor to FCP 7. As far as the other FCS apps are concerned, nobody knows yet. I'm guessing that due to the announced $299 price tag of FCP X, Apple would have no reason to continue developing FCE.
Further, depending on how FCP X handles pro workflows, I wouldn't be shocked if Apple continues to ship the FCS 3 suite. There are a lot of unanswered questions in that area and I just don't see professionals (especially studios, post houses, etc.) making an immediate transition if a lot of the workflow tools they're accustomed to using suddenly vanished.