If everyone holding tether attempted to redeem their tether coins for USD in rapid succession it would implode. Of course, if tether were telling the truth it would be an operational headache but otherwise a non-issue.

There’s also a certain point where they can no longer “print” coins that are believably backed. If tether is to be believed (and, for the record, I’m of the opinion they shouldn’t be) then they’re already responsible for an absurd portion of the commercial paper market.