Bitcoin will always be the POW king, but I can foresee some good competition from a POS or other type of staking method that is more energy efficient.
I agree with you. Nowadays Bitcoin is an undisputed leader though it's a lit bit late to start mining , better to buy some coins and get profit from buying/selling strategy. Even it's volatile it's less volatile than altcoins because of their little credibility, altcoins, I think, is going to replace Bitcoin. And it won't be Litecoin to replace BTC as it's dead.