@hv:
I however do not get your point with the Nash equilibrium ...
Ok I 'll try it again:
There are two main powers that work against the centralization, which is a classical fix point problem where the attractor is given by the positive returns from mining profits - really, this equation has no varaible in the type of the algo, so you can chose ANY - all efforts to find a better one is net negative! Physics can save you lot of work here, but feel free to learn that hands on.
1. External forces, that destroy any (artificial) order in this universe, better known as entropy or dissipation at work/ fricktion. Here all operational risks fall in, like lump risk (to high centralization, compare big datacenters with no proper backup!), desaster risks ( fire, sonic shocks, war,...) and also regulative risks (China!), technical development risk (some better ASIC or quantum tech), here can be lot more other risks be named!
2. Nash Equilibrium / inner force: Since all bigger players are aware of the real need of a 'decent' decentralization, there is a pressure ( inside of each player) to NOT create a monopoly. Why? -> Reputation risk! Once the other players notice the monoply, they will fold the game and leave! We've seen this with a pool reaching 50% some years ago. Where is that? Gone!
I predict that china pools will never really collude, only for the reason to destroy bitcoin ( could be a short time event with potential revival) and go for bitcoin cash?