I think the most likely outcome is that governments will become the largest miners to secure blockchains. The security of a blockchain is a public good. There'

I think the most likely outcome is that governments will become the largest miners to secure blockchains. The security of a blockchain is a public good. There's no need to regulate computing capacity when you have the power to tax enough wealth to ensure that the government always has more computing capacity. It's an arms race without the nuclear winter, and with the side effects of increased pollution and rapidly advancing processing power.