I agree that it has the potential, but I think that this is unlikely. The approach to generating the incremental revenue can be done in at least two ways: claiming expected value and creating additional value. To use two free-to-play games as an example, consider League of Legends (LOL) and Dota 2. LOL requires one to use either purchased currency or earned currency to unlock characters. Dota 2 immediately makes all characters available to play. Therefore, a Dota 2 player would expect to have that value, yet it must be purchased through time or money in LOL. Both games, however, create value through the selling cosmetic enhancements to heroes.

If you think about it, the demo model seems like a special case of the free-to-play model: a small amount of content is free to play and the rest of the content can only be accessed through a purchase.