That's such a refreshing topic @ga38jem

I did asked myself number of times what would happen if last BTC would be mined. And I've tried to imagine what would have happened. And all I could find were more questions.

If miners would not be rewarded for mined blocks - then who would mine it?

To be honest, I don't even think it will be profitable for miners to mine even before we will reach that point of time. Even months before - it will be probably not rewarding enough to be profitable. The only way it could still be profitable is by reaching some insane price levels for BTC (So even super small fraction of minted bitcoin could cover costs of electricity).

If public institutions hold BTC after the last one is mined and they find out that the miners are about to shut off their mining rigs because they are not making profits, they would not hesitate to pump some money into these mining rigs to keep the whole thing going.

I kindly disagree. Those institutions will very unlikely take on their own shoulders building/replacing infrastructure of miners.

I can easily imagine that regulations would not allow them to be involved in any shape or form.

Post resteemed and upvoted
Cheers, Piotr