I mean, that's basically what Dark Sun did. It's a setting that tables a bunch of classes for either being arcane (when magic has gone haywire) or divine (where there are no gods) and then radically changes the remaining few to fit that design. No bards, sorcerers paladins, or warlocks, highly changed clerics (if allowed) and wizards, and that jury is out on monks.
Could any company sell a product where the possible classes are fighter, rogue, barbarian, druid, and highly altered cleric and wizard? Could it even further limit subclasses so that there is no eldritch knight or arcane trickster for example. Even with a psionics system to do a lot of heavy lifting (no small task) you have a lot of game mechanics in classes alone to design. And that's just classes, we've not touched spells, gear and feats.
Which I think is why no 3pp has done this, unless they are going out of genre or using an IP. And if it's a hurdle to a 3pp Kickstarter, it's a hurdle to WotC. Ultimately, I think if we ever did see a Dark Sun, you're going to see all 12 PHB classes represented, even paladin.