SimCity will require an internet connection to play
Speaking to Joystiq, SimCity Lead designer Stone Librande has revealed that the new SimCity will be an "internet-dependent experience." You'll need to stay connected to the net through Origin if you want to keep playing. He cited SimCity's multiplayer features, like the global economy that will let players sell excess resources on a massive connected market, as the reason for the always-online requirement.
Though SimCity will maintain its connection through Origin, we won't have to buy it through EA's digital store. SimCity will be available to buy through other digital distributors, and at retail, but that's small comfort for those with unreliable internet connections. As we've seen with Ubisoft, you can have the most stable connection in the world and still be at the whim to server switches and meltdowns at the developer/publisher end.