The EU seems like a more stable thing than the US these days. Japan has always been a stable thing. The west can’t really do India or China, but those would also make better options than the US right now. It’s not unprecedented for people to flee the USD.
You're missing the point. There's not enough Euro or Yen denominated assets to make that work.
https://www.nber.org/digest/apr20/why-euro-hasnt-become-inte...
That's just an accounting problem. Once the countries start dumping dollars and buying Euros, the ECB can just create new Euros out of thin air to prevent it from appreciation.
Your own link basically says: "dollar is more stable and scalable, so people use it".
Could always move to a basket of currencies, that’s been proposed before