My problem with it is that it will only last as long as the servers are kept online by the publisher.
...now ask yourselves: how long until SaveSimCity becomes neccessary?
Ugh, I know there's already an example of this somewhere... where they simply... oh! Remembered it while writing!
Dragon Age: Legends, the former Facebook game - they changed it to a solo game that could be downloaded by the players when it went out of business, they modified xp and such so that it would be less of a timesink.
One would hope that this will be their fate when these games are no longer supported.