I wanted to scoff at this, but I guess being in the sky will allow for zero-G effects and stuff.
My initial reaction was "great, the threat of the sky is to fall, which means platforming" but I can now imagine a hallway splitting open and assholes falling to their doom while the contents of the room float about perilously.
Honestly, if they just went back to space like with System Shock, they would be able to do most of this, in addition to everything BioShock threw at us. I guess it's about setting, and I'll admit that it is a cool one (reminds me of Metroid Prime 3) but it's still Rapture in the sky with some stupid ass 50's theme.
edit: thank you for pointing out my ignorance, Eusis, but I still don't care for the old timey presentation.