I'm surprised there are so many PoW coins out there, when there's so much propaganda against them (particularly by mainstream governments). It looks like PoW won't become "extinct" anytime soon.
ASIC miner producers are billion dollar companies. They are not going anywhere and keep releasing new miners.
In terms of POW altcoins like Kadena, you shouldn't mine them 24/7. Miners are always checking the most profitable coins at the moment. So you may buy an ASIC miner for BTC but switch it to Kadena for some time (can be even a few hours) once rewards are higher so you don't need to buy expensive equipment for alts only.