Oh man, that would suck. I do not ever use an external USB port for that exact reason! Aside from a few desktops and laptops around the house all my equipment has an internal USB port for the purpose of a boot drive (I always assumed that was the reason).
All production stuff needs backups. Personally I try to keep boot device backups saved to another device as an image so if one goes down, I can clone it to a USB real quick and restore the blink to the lights; ideally I should also keep them off site, but I don’t like to use cloud providers (tin foil hat and all).