> If all the miners are gone, the difficulty has hopefully dropped precipitously
AFAIK there is no mechanism for the difficulty of new blocks to fall. And if the only use is creating transactions between yourself and yourself, well you can also collect gravel.
> This doesn’t sound super useful, but it sounds about as useful as a bar of gold in a world where nobody considers gold to be valuable.
Even in a sub-industrial context and ignoring pretty much all of human history and assuming your gold has lost all of its extrinsic worth, your bar of gold could be molded or cast into plenty of useful things (light reflectors, heat shields, baubles, weights). Bitcoins, not so much.
The catch is that the difficulty adjustment only happens every ~2k blocks. If a mass exodus of mining capacity happens really quickly, it could leave the network stranded. But if they leave at a reasonable pace, it will ramp down. That’s why I said “hopefully” before.
AFAIK there is no mechanism for the difficulty of new blocks to fall. And if the only use is creating transactions between yourself and yourself, well you can also collect gravel.
> This doesn’t sound super useful, but it sounds about as useful as a bar of gold in a world where nobody considers gold to be valuable.
Even in a sub-industrial context and ignoring pretty much all of human history and assuming your gold has lost all of its extrinsic worth, your bar of gold could be molded or cast into plenty of useful things (light reflectors, heat shields, baubles, weights). Bitcoins, not so much.