I’m wanting to run a 5e game, and to merge it with Dark Sun, I want to run a west marches game. West Marches games can be described here: https://knightssemantic.wordpress.com/2016/06/01/the-west-marches-a-style-of-dd-campaign-for-large-groups/
It would work by having the outpost be at the edge of civilization. Magic and divine power from the “old world” works well even while in Athas, but things from there cannot use it. It would be a hybrid to not be restrictive to players wanting to play different classes. The problem is that I got stuck on various ways to adapt 5e, make it feel like dark sun, and not make the entire experience monochromatic (you are in a desert with bandits for 500 miles).