No matter what happens with PoS, a world wide ban of PoW mining before 2030 is very probable, and that is a very real danger not imagined conjecture.
You can't realistically stop PoW, by banning it. There'll always be people who'll have access to computational power and therefore, can always use it to mine cryptocurrencies. Besides, isn't it already proven that the majority of the hash rate comes from renewable sources?Energy prices going up => Electricity prices rising => Government announces planned power outages. Which are terrible because they wreak havoc on filesystems in Linux (non-RHEL) machines even if they are shut down cleanly and are backed with UPS'es (wrong freed block/inode counts galore
)I have just recovered from the 3rd power outage today. It wasn't fun at all. I have no idea if there's a huge mining presence where I'm living now, but these kinds of governments are usually the first to take an action against PoW coins. A reduction in mining difficulty corresponding to a ban would almost certainly see BTC's price go down by some significant percent (we are talking between 20-30% depending on the severity of the ban).
It doesn't have to be PoS but any other proof that does not rely on using coins to influence difficulty can be dropped in-place of Bitcoin's PoW (such as my example proof of time) in a scheduled hardfork if the time comes.