Agree that the EU will more likely break up than the US, there aren't state-level checkpoints banning interstate travel on a governor-by-governor basis. If Germany and Austria are squabbling over medical supplies now, it likely won't be EUR.

I doubt CNY given past history, but if the worst comes to pass, I don't think China would pass up a long-shot opportunity to become the next reserve currency. I think it depends on how desperate people are, and how good China's execution is. USD took off post-WWII and USA's execution was top-notch.

I would also say not having a global reserve currency is another option, especially if globalization shrinks massively and international trade becomes highly discrete and easily manageable at a national level by govt. I think there are some trade deals that are barter-like (Australia // Taiwan with the alcohol for masks trade). No need for USD there.

Let's hope the USD is here to stay, and the country stays strong. I just hate being surprised.