I've heard the steady state 20-30 years out described like Steve Barbour does in the clip below, but to me this gets into really iffy game theory territory. If the hashrate is both variable and flexible, and the block reward is variable (which it will be due to fees taking over) you get into some really nasty dynamics where fee-sniping and fighting over blocks is going to lead to coalitions forming, which will eventually lead to centralization.

What are other models for steady state of Bitcoin mining, say post 2045?