I really think a sequel would ruin Bioshock and its meaning, but that's just me. I believe this is not a game to continue, 2k might have said that they considered doing more with Bioshock, but I believe that doesn't mean a sequel.
2k should indeed go on with their gaming career, because 2k boston and australia proved to me that they really mean business. I don't want to see another Rapture, I want to see another masterpeice that they can craft.
I would like...meh, maybe a prequel series? Maybe a prequel game. I agree with tsuyu, the downfall of Rapture is like the downfall Rome, it should be something everyone should know about
The story arc is just waiting to be unraveled, not continued. There are so many secrets in the world of Rapture, and i'm dying to find out what.