Update 10, which brings offline play to SimCity for the first time, is launching today after successfully coming through final testing. An announcement on the EA forums reads, "Today at 6AM PT we will be releasing Update 10 with Offline play. This involves server down time and the game servers will be unavailable for a few hours."
EA unveiled Update 10 and the new single-player mode back in January, after a 2013 in which the publisher came under severe criticism for implementing an "always-on" system for the city-building sim. That system backfired when servers buckled under the weight.
EA has already said players can access their previously downloaded content in the single-player mode, and they can save their files locally. A new FAQ reveals players still have to sign into Origin to launch the game, but Origin can be put into an offline mode while the single-player mode is being played.