The DEX won't censor trades linked to stablecoins.
They already are censoring certain jurisdictions, so why wouldn't they if such laws come to place? Sure the DEX isn't censored on chain it is only the website, but very few people could use a DEX like Uniswap without the website.
But what use would that be if the stablecoin issuer itself can put you on a "blacklist"?
They can and they already do this. They just can't know your addresses in advance, but as soon as they know an address is yours they will freeze it.
The problem is that most decentralized stablecoins aren't reliable as their centralized counterparts. Either they're algorithmic or collaterized by other cryptocurrencies.
Algorithmic stablecoins are garbage.