I definitely think that proof-of-work is going to be phased out soon, though proof-of-stake isn't much better, they all require specialist hardware in order to run their networks, which is not something we should implement for later generation blockchains, a waste of energy can't be the best way to secure a blockchain. I notice that the major blockchains are starting to shift towards POS as it's definitely more environmentally friendly than POW, but it also increases centralization and the risk of a vector based attack so we should look for even better alternatives in future.
No way. There are exactly 0, zero other coins out there that can outperform Bitcoin's pure PoW approach specially as a store of value, and probably not any of these other projects, be it PoS, or any of the more exotic variations, may not deliver a better solution than a second layer solution on top of Bitcoin's POW blockchain when it comes to day to day payments.
Some are trying hard and they will basically be competing against Bitcoin's LN. Will you trust their project above LN to pay for a coffee? will you even bother going into another token at all? that we'll have to see.
Lets not get too complacent. I remember a time when myspace was the dominant social platform, I remember a time when VHS was the preferred media format, I remember a time when the simpsons was still a good show.
The point is lets not pretend that a new coin won't come along in the future and dethrone bitcoin.