As for other altcoins, they do their own thing. In fact with ETH failing to pump and give the bag-holders the profit they dream for, it creates the opportunity for other coins to be pumped bigger by pulling the liquidity from the dumping ETH market into their own pumps.
Ethereum is one altcoin that has massively failed to grow when compared to how long it has been around. Should it continue this way in its disappointing underperformance till the end of this season's bull run while bitcoin makes and recreates ATH's without eth reciprocating, then a lot of ethereum hodler would be forced to find other alternative coins for sure which will definitely see to ethereum becoming a totally shitcoin by next season's bull run circle with other well performing coin(s) taking it's position behind bitcoin.