In a recent interview, 2K Games Global President Christoph Hartmann spoke about the potential longevity that Bioshock has.  Hartmann stated that it was possible to get as many as 5 more games out of the Bioshock franchise because of the depth of it's universe, but was very weary about overdoing it.

He said the key was in striking a balance.  Hartmann reassured fans that 2K would not simply cash in on the series, drawing parallels to the Matrix movie trilogy or the Need for Speed franchise.  In both cases, the quality of the franchise was called into judgment after the subsequent sequls were released, saying "it’s hard to believe what they’ve done to it. It’s upsetting, actually".

Hartmann instead compared Bioshock to the more favorably received Star Wars line, saying "If we spin it the right way and get the right twist of innovation, we can make six parts of it, as Star Wars did".

Bioshock 2: Sea of Dreams is currently in development by 2K Games.  It's due out in 2009, for both the PS3 and the XBox 360.