One of the major hurdles for DEX is creating liquidity pools. With major DEX especially Kyber network and 0x advancing and working towards launching the DEX with propr liquidity I think this challenge of liquidity will be solved. DEX is the future of the crypto and also the theme for 2018.

PS you missed the following great Decentralised exchange projects:

0x protocol plus several DEX apps being built on it like Radarrelay
Kyber Networks
Block
BCO
NEX