An RPG, especially a TTRPG is entirely the product of your imagination with a few rules to kick start the process. Those rules can be written by anyone and indeed I would encourage role players to do exactly this!
In other words it doesn’t matter if Hasbro decided to delete the whole range of D&D books tomorrow because nerds will do what we have always done: write our own stories.
In my day all you had was a pen, paper, 2nd hand warhammer models and some old Space Crusade boards. These days it’s almost laughably easy to collaborate with others online, 3D print your own models, digitally design your own boards and play your own game.
This all belongs to you.