"Distribution rights" aren't laws of nature. If you're making physical media, you get a license to sell physical copies of the game (containing the licensed material) for a limited time, to people who are allowed to keep them once your sales license has expired.
The digital equivalent would be: you get a license to sell digital copies of the game (containing the licensed material) for a limited time, to people who are allowed to re-download them once your sales license has expired. (And you are allowed to provide that downloading service, but not continue to sell the games, nor make them available to people who have not purchased them.)
It's not that hard – and the existence of Steam demonstrates that many people are already doing things this way.
The digital equivalent would be: you get a license to sell digital copies of the game (containing the licensed material) for a limited time, to people who are allowed to re-download them once your sales license has expired. (And you are allowed to provide that downloading service, but not continue to sell the games, nor make them available to people who have not purchased them.)
It's not that hard – and the existence of Steam demonstrates that many people are already doing things this way.