User blog comment:D.Ryan/Did Bridgette Tenenabum Die?/@comment-939754-20100225003632

I think it was left open for a subject BioShock 3 could use. If you pay attention, they left A LOT of open ends in this game. I think they wanted many options to make BioShock 3 from.

She says there's others that need her and leaves that place. But the audio diary says her sub was destroyed. You'd have to assume she's still in Rapture when you leave, so who knows what happens. :)