Conveniently delayed just long enough so that people who weren't considering upgrading to Xbox One from Xbox 360 might get impatient? I find this completely shocking
As for what happens when you get disconnected.. well it's an online only game, so you're getting dumped to the menu, just like if you were playing COD multi. Have they confirmed an offline bot-mode? I'm sure they could do that without 'cloud'. I think the idea of how cloud processing helps is that normally for say COD, when they have the player-hosted multiplayer (the one where someone quits and you get a host-migration), that hosting adds extra strain to that player's system already. AI would have to run on that player/server as well which would slow it down even more, and it would also add to the amount of data sent by the server to sync the game state.
I think an offline mode running the same AI is perfectly plausible, as I don't think there is anything special about the AI in the game.