As unrealistic as it is for stablecoins to become illegal, even if it did happen, there would still be alternative options. CDP stablecoins aren’t backed by US dollars and are fairly decentralized. There are also Euro backed and Yuan backed stablecoins. Trump isn’t dumb enough to do something that would hurt dollar adoption and help out competing currencies.

As for whether it would kill Ethereum, the answer is no. You just have to look at Solana and XRP to see that people will still buy altcoins for other reasons unrelated to stablecoins.