...and what exactly will they do about it? The question is about decentralized exchanges. Countries may choose not to "tolerate" whatever they wish, but the internet is under no compulsion to tolerate shortsighted countries.
That would work, I guess, but that is a huge step to make and governments aren't currently talking about how they plan in banning all of Bitcoin.
I can't see that ever happening especially because these protocols would have non currency uses as well.