I could see it as well. For me currently, I’ve completed 100% of the Spanish course, and I’d like to keep learning more, but there’s no more content. I think there’s a lot of more legitimate opportunities they could find, in the way of more content, to keep me coming back. Right now to be honest I just continue using it to maintain my streak, since I’m already fluent. But! I’ve recently started learning Italian, and maybe that way they can get a couple more years out of me.