I think this is a fallacy. Maybe the big developers wouldn't have incentive to develop billion-dollar cosmetic-powered games anymore, but someone would make it

I think this is a fallacy. Maybe the big developers wouldn't have incentive to develop billion-dollar cosmetic-powered games anymore, but someone would make it work financially. You'd still have hugely popular multiplayer games, and maybe they would be somewhat less ambitious in scope and features (i.e. dev cost), but they would still be fun, and have strong communities built around them. Maybe they sell DLC map packs (which would not have the "community fragmentation" problem from today's centralized matchmaking if private servers exist), or figure out other ways to generate incremental revenue. Or maybe they don't, and just sell the base game, and are still successful because it's not a 5,000 person team and a nine-figure budget. Today's games don't exist because of the business model, it's the other way around.