I agree that this is what it will look like if it takes off. But then those "couple of big sites" will have all the same incentives / problems as the current ma

I agree that this is what it will look like if it takes off. But then those "couple of big sites" will have all the same incentives / problems as the current mass market sites, and will themselves be enshittified eventually. The model needs to somehow result in distributing the user load and thus the costs across many hosts such that it is a bearable cost for each individual host without requiring any deep pocketed support. But you and I are in agreement that that doesn't seem like the likely outcome.