Why does a reserve currency even need to exist? Bretton Woods was a result of the extraordinary circumstances of WW2. The move to the petrodollar was a good deal at the time letting the US play world police. Now it's clear that the US isn't a reliable security partner even if other countries wanted it. The oil producing nations would surely be happy to start selling in other currencies.
You're always going to have one currency that is used for most of international trade, because it's much cheaper for country A exporters and country B exporters to settle in one currency. 1-N systems are generally stabler than N-N systems.
