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.
Discussion
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.