Apparently BioShock Hasn't Been Removed From The App Store For Good
Some warning would be great next time, though.
After removing the mobile version of BioShock from iOS recently from the App Store and deleting the game from buyers' purchase histories, it was assumed that 2K would be going down the path of EA and just getting rid of certain games without any sort of fanfare or explanation. It turns out that isn't the case, and BioShock is instead being pulled to be reworked to support iOS 9.
2K's statement reads as such:
"2K recently provided inaccurate information to customers surrounding removal of BioShock for iOS from the App Store. BioShock is currently incompatible with iOS versions 8.4 and higher, and as such, is temporarily removed for purchase from the App Store. 2K is fixing the compatibility issue, and when resolved, will place BioShock back on the App Store for purchase. Customers who already own BioShock may continue playing the game with iOS version 8.3 or earlier. 2K regrets the initial customer service error and looks forward to delivering an updated version of BioShock for iOS in the near future."
So it seems we're getting a reworked copy of the game, but it's bizarre that this wasn't communicated ahead of time. What's the deal with that? We may never know.