They still have not said that it won't be possible to buy it with in game currency. So its still up in the air. The only thing we know for sure is that they will be available for real money and there will be short tutorial single player adventure for free
In the not-too-recent past, major game reviewers used to bitch when a first person adventure shooter didn't have a multiplayer component, or had a substandard one. Putting the shoe on the other foot, however, hardly ever has there been a review that complained that a multiplayer game didn't have a single-person adventure included with it.
