I think you underestimate the power of Government to affect this. They could go after Amazon and demand that it become 4 different businesses: AWS, the marketplace provider (no products), the product companies, etc.

They could also pass various laws limiting or taxing large companies. I don’t expect this to happen in America as these are American companies, but Europe is certainly getting wiser to allowing foreign companies to have this level of influence.

Otherwise, the world is sunk.