Monopolistic control is clearly a problem, and all the barriers (money for GPUs, regulations that pull up the ladder, hoarding of user data, ability for big companies to copy smaller ones, etc) make this AI transition problematic unless we also come up with new easy to enforce antitrust regulations.
But I think an even bigger issue is that these monopolists are all closed source. Open source in AI means we should be able to reproduce their exact model. Everything from training data to censorship filters needs to be transparent. Otherwise we really have no idea how we might be getting manipulated through these systems, whether by the company providing the models or those who can regulate or pressure or otherwise control those companies.