What are the big names? Paizo/Pathfinder? Can't they simply do their own thing and stop relying on D&D precisely because they are so big their customer base already knows them?

Or is it computer games? With computers handling the rules, you can just make your own RPG rules, right? Or is it the setting? Do people really only play videogames that are set in Faerun or Icewind Dale or whatever? Can't you just make your own stuff up and call it Arda-- er, Middle-- er, Ancient Magical Land of Elves?