Fortnite might have been free-to-play, but Kodera noted that "add-on and download sales were notable." This is really important, that though people were required to spend no money in order to play the game on the PS4, they did so voluntarily in order to access additional features. This free-to-play game is a moneymaker for both PSN and the game developer.
Kodera continued by saying that they are exploring various models, from paid game downloads to free to play, in order to maximize revenue. It's an especially important conversation right now, considering that, on the same call, Kodera made clear that the PS4's declining sales means it's not a part of the company's three-year roadmap. The fact that the company has alternative revenue streams, such as PSN, and that Sony can explore how to further leverage free-to-play games to bring in more money