This isn't a case where a client-only software package is locked by a remote server.
This is a case where core game logic is stored on servers and will have to be reverse engineered or emulated on some level to play truly offline.
Granted, anything having to do with the region (imports/exports, shared upgrades, etc) was defunct.
Additionally, when you exit a city, there's a long pause where your client sends the city state to the server to be persisted (or so the UI tells me) -- another indication that the simulation is not run on the server.
My current impression is that the entire city simulation is done on the client, and the server is simply responsible for intra-city interactions and persisting game state.
I'm going to keep poking at this thing, so I'll document what I find here: https://gist.github.com/deoxxa/5111644 - feel free to join in!
Ultima Online was completely reverse engineered and then re-deployed to host the cracked version at a state where lots of players liked it. Prior to the devs breaking the way some users preferred it.
Do I doubt this will happen, No. Do I expect it to happen tomorrow? No.
But I expect either this to happen, or EA to fix this problem. When its fixed, I'll buy the game.