THIS!
Although, I suspect that fees will not be 1000 sats/vbyte in decades to come (maybe for rapid settlement), but rather the equivalent purchasing power of something like 250 sats/vbyte today. People will find scaling solutions more attractive with anything much higher than that, and that will lower demand for block space.
Agree with your points too. If Bitcoin has 10x in purchasing power then I agree the sat/vb will be nominally less. Something like $100 in fiat to tx on chain possibly whatever that equates to in sats at the time.
I bet it'll hover somewhere between our two guesses then, the equivalent of 25 to 100 dollars today. I definitely don't have all the information needed to be confident in my prediction or yours, but your guess and your reasoning smell right to me.
