I understand the hypothetical trend being mentioned, and I would even agree with it in absence of stablecoins. See, today, if China & Russia want to trade, they may trade in Ruble or Yuan. Ruble or Yuan don't have to be universally accepted for them to trade. But if I am transacting in stablecoin, I don't want to use anything that is not universally accepted from the get-go. Otherwise, I might as well use Ruble or Yuan. So, even if in theory the stablecoin could be backed by any currency, I am not going to use just any stablecoin, only the one most widely accepted.

In other words, I think Stablecoin is winner-take-all, and USD has already won.