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.
It is not going to happen. I can't see any altcoin outpricing Bitcoin in terms of value right now unless it has to be a new and more secure cryptographic currency that has none of the disadvantages bitcoin currently faces