This is hardly a new concept, Eve Online is a fairly prominent example of a game that is run entirely as a subscription service. I'm sure there are other MMO games that do the same, however there are others like World of Warcraft which combine a subscription service with a "boxed" game client.

In the context of the current discussion, I think EA could have made the new SimCity game entirely service based, like Eve, giving the client software as a free download and charging for access to the server, where most/all of the actual simulation logic would live. Instead they've pulled a bait-and-switch with a boxed product.