If you think about it, the implementation of the Starter Edition is very similar to many F2P models.
You are given your own limited play of the game and find that in order to play all of it you have to purchase addons or additional features.
I know the Starter Edition lacks the revenue generation of typical F2P models and in that it stands apart but with this change, and the fact that Blizzard already has a successful e-shop outside of the game, it can't be long before the in-game store appears.