The problem will solve itself. People unwilling to sign up for a mobile plan for playing a game will automatically boycott the likes of Overwatch 2, which will result in revenue lost (perhaps to competing games that allow prepaid cards).

I have only ever used prepaid cards. I would rather be cut off from communication (or buy a local prepaid card) than get a surprise bill of hundreds of euros for visiting a country outside the EU.

I guess a lot of people have the same thought process as me around Europe, because there are lots of smartphones available with dual SIM cards.