If Bitcoin dropped PoW and miners switched to other PoW cryptocurrencies, then that would be a huge reduction in power consumption worldwide because all the other PoW coins combined probably don't have the transactions Bitcoin does.
Additionally, the Lightning Network drastically cuts mining power consumption.
No they are not. For mining a block of BTC a miner gets a reward of 6.25 BTC. Transaction fees, by looking at the past few blocks, don't go much beyond 0.05 BTC. That is not even close.
Additionally, the Lightning Network drastically cuts mining power consumption.