While I disagree when Bitcoin maximalists say, "There will be only one chain", I think there is a kernel of truth there.
Power laws matter. But I think that will be within the various blockchains, which each offer different value propositions.
Specifically, I expect to see one main Monero chain (whichever that ends up being) taking up the vast majority of value, with the others eventually falling to less than 20% combined...similar to how BCH is currently only 10% the value of BTC.