There were days when decentralized exchanges like IDEX were truly decentralized and we can trust them with our information. But now they are claiming themselves as DEX but have become more like a centralized exchange. Some DEX could change their terms over time, but majority of them still function in a highly decentralized manner. As you have said, there could be regulations pitching in from time to time but the XMR - BTC atomic swap could probably be a game changer of the industry when realized and when proved successful, there wouldn't be really a need for DEX in future transactions. OTOH, centralized exchanges like Binance do charge a hefty fee on its users during withdrawals and have a poor customer support for issues hence DEX could always prove to be an alternative to these highly expensive centralized exchanges.
If an exchange to function properly like Binance DEX, they should be regulating them properly so that there aren't really huge malicious transactions going through them.
As long as crypto/Blockchain tech is considered to be a threat to the existing monetary system, we'll expect constant opposition by governments worldwide.
Possibly the digital yuan could be a new entry to blockchain space backed by government. They are still on the initial testing but China has been spending millions on the tests so that they could be proven as a really good competitor and could possibly replace currency like Tether in future? India on the other hand, has been planning to issue Digital Rupee thereby banning cryptocurrencies which could pose a threat again, but currencies like XMR which is highly privacy centric might become the future of digital trades if bitcoin were traced back to owner on higher scales by government.