If you are thinking of the free to play model with microtransactions, I do not think that it would work as well for single player games.
What I do know is that illegal consumption of games leads to increased legal consumption though
https://arstechnica.com/gaming/2017/09/eu-study-finds-piracy...
If you are thinking of the free to play model with microtransactions, I do not think that it would work as well for single player games.