1/ Many claim that "bitcoin dominance" is a meaningful metric. Looking at the data, it doesn't appear that demand for bitcoin has shifted to alts/tokens. docs.google.com/spreadsheets/d… 
2/ The following protocols are not substitutes: a decentralized store of value, a world computer, a cheap payment network, a cloud storage system, a supply-chain tracking log, a prediction market, a bank-communication platform, a stablecoin, etc. techcrunch.com/2017/11/19/100…
3/ The only thing these "coins" have in common is that they use (ancient) cryptographic primitives, are written by software engineers, and are inspired by Satoshi Nakamoto's work. It's only because they are traded on the same exchanges that people think they're easily comparable.
4/ What happened in 2016 to mid 2017 wasn't that bitcoin lost "dominance", it was that demand for utopian blockchain promises skyrocketed, while demand for a censorship resistant store of value only increased by 1-2 orders of magnitude.
5/ Notice that these demands were uncorrelated, yet many think "the cryptocurrency markets" only move together. As projects mature and tribal lines solidify, prices will become more decoupled over time. In retrospect, the "index" approach will seem very misguided. /fin
