Shinook: I'm not so sure it's that easy.
Isn't it like Diablo 3, where the content is generated and stored server side, then transmitted to the game client?
Starkrun: There is already an offline working single player Diablo 3, it was made just a few weeks after release... and the Playstation client is offline as well with 4 player onscreen co-op. Short version no server needed to play the game, all generated code can be client side.
sadly the Playstation version has better drops more loot and plays like Diablo 2... the PC version has drop restrictions on anything rare and greater due to market flooding with goods.
Don't get me wrong, it's definitely possible, but it's not as simple as patching out the code that checks in with the servers. You'd have to emulate what the client expects the server to be doing locally, either by replacing the code that does the communications with the server or by emulating the server itself. In either case, EA is unlikely to go through that effort for a title they've abandoned.
If someone wanted to spend the time to reverse engineer the game and it's map/item/character/etc generation mechanisms, then replace it with something that does it locally, it's definitely possible. It's also a significant task.