That's a thought. I can imagine a few MMORPGs trying this out in the future. Integrating their own cryptocurrency which will both act within the game, and an investment outside of it.
MMORPGs are in desperate need to reinvent themselves or the market will eventually weaken even more! I've seen some private and independent servers trying it out (not with crypto tho). I believe in the future this is going to be a feature at least with some gaming genres!