Bitcoin would continue to appreciate to infinity while an economy would shrink because nobody spends.
what if satoshi is an alien sent from his planet to conquer the earth and bitcoin is basically.... like a memetic virus created to destroy civilization with a tulup bubble that never crashes, it just inflates and inflates until everyone dies.
that alien will fail because btc would simply never reach widespread use in that scenario and everone continues to use fiat. the prevention for "being tricked" is people like me and many economists raise the deflationary spiral concern.
the endgame with a deflationary currency is that its value grows exponentially and then explodes to zero. just like tulip mania.
this might be why btc is so volatile these days.
Anyway it's not at zero now because the jury is still out on if btc can address the fixed 21million supply in 2140. it might be addressable by instituting a fractional reserve/lending system. of course, the ability to create one in a decentralized environment has yet to be proven.