In regard to gov/big corps keeping Bitcoin mining up.

Big corps will not be able to mine in the far future and governments will only be able to mine through deficiet spending up and until their currency doesn't work anymore in which case they'll either have their own energy sources, or bust.

This is because we're starting to see solutions for Bitcoin mining which work while being entirely unprofitable. Things like Bitcoin mining heaters to replace space heaters (the water heater idea is not looking good so far but hey maybe one day it'll work out).