Most new coins are moving away from PoW, so probably the party won't last long. When Ethereum goes PoS everyone will switch to smaller coins, making none of them profitable. There's won't be big new coins to replace Ethereum.
but i think when they switch to smaller coins ,the price of smaller coins will rise.
Mining raises coin offer, lots of new people trying to sell, same people trying to buy. How is that going to rise the price? Market logic says mining will tank the diminish value by raising offer without raising demand.