According to the latest chatter, Treyarch's next Call of Duty game will be a direct follow-up to last year's Black Ops, potentially creating a new sub-franchise as Infinity Ward did with Modern Warfare.
There's no surprise that Treyarch is working on another Call of Duty because ... what else would it be doing? That we could be looking at a Black Ops 2 is the interesting point, but again, since the last Black Ops was Treyarch's most creatively successful game, it's hardly a shock to think that it'll be doing another one.
That's the word on the street, anyway. Treyarch's bumping up its staff for Black Ops 2. Do what you will with such gossip.
Treyarch’s next a Black Ops sequel? [That VideoGame Blog]