Saying alt coins will die off is as dumb as saying, we only need 1 company in the US to do everything.
Every alt coin will fullfill a certain niche, the ones that survive at least.
I don't believe will ever have one blockchain that's mass adopted. It means too much control.
We'll have niche chains, and they will tie in together like a web. Kinda like Local networks tie into the world wide web.
RE: Steem Monsters races past EOS knights on stateofthedapps.com