The way I understand it decentralized exchanges only enable you to trade tokens of the respective blockchain that they are based on, or am I mistaken? Because this unfortunately significantly narrows down the selection of tradeable assets.
I love seeing how much work is being done on decentralized exchanges, but as long as these constraints apply their utility is rather limited.
Wavesplatform is a work in progress, not only tokens related to its blockchain are tradeable. Coins like LTC, ZEC, ETH are tradeable there. And there is plan to support ERC 2.0 tokens too.