BTC dominance is far too high and I hardly doubt that an altcoin will replace BTC one day. I prefer to use altcoins, but the majority of investors still believes in Bitcoin and sells all their altcoins to get some extra BTC.
The market situation is indeed not possible to buy ALtcoin, so investors sell altcoin assets to become BTC. BTC dominance is currently still too high. But there will be a time when BTC dominance goes down and will be replaced by Altcoin. There are still many opportunities for altcoin.