I think there needs to be some clarification as to the nature of why the game thinks it needs to be always online. Some people have suggested that ALL the computing and simulation logic happens on EA servers, but this isn't true.
It has been shown that if you lose a net connection/connection to the server, the game will continue to run offline for about 20 minutes. During this time, YOUR city will continue to simulate properly. However, neighboring cities being developed by other people will freeze in time and be held in this state until such time that your connection is reestablished (if it doesn't before the timeout, the game session ends). Once it reconnects, the state of your neighbors is synced with your city and hence any changes to your neighbors' cities during the time you were offline will immediately be represented.
If you connection drops, your city lives in isolation. Once it reconnects, it returns to the world and is affected by the effects of your neighbors. If you happen to be developing a city next to a tard who is polluting like crazy, your city will suffer the effects. That's the whole purpose of the always-online feature - to provide this MMO-style relationship between players. BUT, given the game runs fine with your city if the connection drops, this is bullshit because it means it should be trivial to enable the player to just play on their own.
The simulation logic is there, available on the installed game. EA just doesn't feel it's worth having an offline mode despite it basically being readily set up for it - it thinks being interconnected with other players who might be dicks and ruin your city is much more important.