Well, clarifying the mystifying "Not always online but does require an internet connection" bit from the Q & A, Microsoft just told Kotaku that while it doesn't have to always be online, you do need to connect to their "cloud" once every twenty four hours to keep doing stuff.
I'm really hoping this is just--like how the used game thing seemingly is--some kind of miscommunication.
Here's the money-shot quote:
Kotaku: If I’m playing a single player game, do I have to be online at least once per hour or something like that? Or can I go weeks and weeks?
Harrison: I believe it’s 24 hours.
Kotaku: I’d have to connect online once every day.