

The end of the USD Reserve status is going to cause an absolute shitload of harm in the US (at the very least, huge inflation) but how much damage is it really going to cause elsewhere?
The US isn’t a keystone nation in most manufacturing processes anymore, nor does it produce anything that nobody else does: Modern day America mainly exports Social Media and enshittification. Even things like cloud services are provided by datacenters all over the World with the ones based in North America serving North America.
The greatest value of the US for the rest of the World is as a big consumer market for their exports, not as an essential provider of anything which is physically bound to it.
Absolutelly, there would be damage, especially for any nation left holding US Treasuries to the end (especially in the worst scenario of a US default), but “absolute shitload of harm” outside the US, that doesn’t seem likely: if the US magically dissapeared today a bunch of multinational companies would see their Revenues fall maybe 15% but otherwise things would just keep on working because very little the US makes is key.
Granted, countries for which the US is a disproportionatelly high export market like Canada and Mexico would suffer a lot economically, plus Israel would collapse without America’s propping up, but beyond that …
The EUR absolutelly is - the EU is a big stable open economy with large Financial Markets a freely trading currency and deep Treasuries markets.
It’s not by chance that over the last 2 decades mainly the EUR has taken a bigger and bigger slice of foreign exchange reserves away from the USD, with by 2025 the EUR being roughly 1/3 the amount of USD reserves (see here).
(That said, looking at that data, the EUR and USD foreign currency reserves have barelly moved since 2017)
Agree on the RNB not being ready - China’s currency isn’t freely traded and neither are their treasuries, and access to mainland Financial Markets is highly restricted. That’s reflected on the above mentioned foreign exchange reserves where the RNB is but 1/10 of the EUR reserves.