I don't think that we have any truly decentralized exchanges as of yet. I do suspect that in time we'll have an exchange that has no entity controlling its development, maintenance etc. Hopefully some sort of open source exchange in which all users are in control of their own funds and the trades that they execute. A lot of DEX's currently are more like hybrids between a centralized and a decentralized exchange, mostly around the fact that they don't hold users funds.