2K could give it to another studio, I just don't know which one. 2K Marine is dead, Rod Fergusons former studio is doing Mafia 3 and there really is nowhere to put Bioshock other then at the hands of Irrational right now.
As for as much creative freedom 2K gives them, they are still at the end of the day a business that needs to turn a profit and that is done by taking that 100 million dollar franchise you spent years building and continuing on. My point is, that they could be as creative as they want, as long as the box 2K ends up selling says Bioshock on it.
Because it made (and cost) a lot of mony to make Infinite. Stopping now would be a waste of investment.