Actually yes, Binance is planning to go fully decentralized at some point. They have stated their the BNB token will play an integral role in their DEX, once it (re)launches. The details are still unclear, and they probably are still in the planning phase. As for Kucoin I don't know.

I think centralized exchanges will remain for the foreseeable future, but perhaps become less popular over time. Centralized exchanges are still much faster than decentralized ones, and currently offer a lot more liquidity. Perhaps this changes in the future... But then centralized exchanges can still offer benefits to users, like insurance (they take responsability for the care of your crypto - some people trust exchanges more than themselves). Large institutional investors may demand certain insurances, too.

They will have to innovate to adapt, and perhaps some of them will evolve into DEXes as well, or become hybrids.
For 2018 I am pretty sure centralized exchanges will remain popular.