If I am not wrong, the domains can be easily seized. And after what happened with BTC-e/Wex.nz, I believe that in many cases the authorities will be even capable of seizing any funds within these DEX sites.
True, but it won't stop DEX source code development or DEX itself, they always could .onion domain (for DEX) or IPFS (for DEX source code).
But then the big question arises. Is it possible for a DEX site to move from normal browser to the TOR browser? I am not sure whether the Java Scripts and all would run without any issues in TOR. There may be a lag as well, as TOR is slower than the ordinary browsers due to the requirement of relaying information to multiple nodes.
Another issue is with the security. Knowing how vulnerable ERC-20 platform can be to hacking, I am a bit skeptical about linking the wallet to any DEX sites that operates in TOR. I am not an expert in TOR, so my fear may be illogical. BTW are there any DEX sites which are active now and running on TOR? I haven't heard of any and would like to try.