It wouldn't have to be a direct sequel. Bring back Thorton and Mina(maybe?) with all new chraracters/plot/storylines etc. That's how most Bond movies are handled right?
It sucks that AP is one and done, but at least we got a game that wraps up nicely on it's first entry. Don't understand the hate towards this game. I almost didn't buy AP because of the reviews, but I'm glad I didn't listen because I've enjoyed AP just as much as ME2 and Red Dead this year. It has flaws, but it is not near the horrible game some make it out to be.
It'll be interesting to see if FO:NV gets knocked for outdated graphics or poor AI.