itch.io

Huh? That is some strange ideas with some strange assumptions.

No, you need not eternal growth to fund a project. To fund it, you need a fixed sum. See kickstarter projects for reference. Big companies prefinance that funding. Then release the game and hope their calculations turn out to be correct and the game makes more than funding did cost. Every unit sold afterwards just increases the return of investment. It is a lot like producing a movie. (And on a side note, the recent Unity desaster was in big parts, because the pricing change could topple those calculations after the fact.)

If you have a game that needs maintenance, you need recurring income to cover for that maintenance. Like hosting the servers of an mmo and paying people for supporting the players and whatnot. If the calculation is good, you could even  forgo the initial purchase price and only collect recurring payments of whatever kind (subscription, ads, in-app purchases etc).

And I do not understand what you mean, that Mojang would fail, if people would not buy the Minecraft game in 10 years. Minecraft and Mojang is property of Microsoft since 2014. You can be sure that they will market their $ 2.5 Billion investment in years to come. Even if no one bothers to buy it anymore, so what? Software is project based. If they continue to invest maintenance in a game that no ony buys and do not develop new projets, that is blatant mismanagement and has nothing to do with sustainability, but with running a company.