It will not be China as it doesn't have a floating currency. That is one of the prerequisites for becoming a reserve currency, that and removing capital controls.

Finally there has to be a certain willingness from other countries to accept this new currency and I just don't see the EU countries conducting all their international trade in yuan anytime soon.

Finally replacing the USD is just one part. The second part is how to stop the next currency from being weaponized just like the USD is/was. Without the answer to that question, then switching to a new reserve currency is just replacing one problem with another.

Bitcoin as the new Bancor.

A stable, simple cryptocurrency is ideal for this. Not only is it not controlled by any nation state, it's not controlled by anyone. It's just there, a tradable asset that has mathematically-defined rules for how many will ever be created. Also gets around the Triffin Dilemma by not being used as a national currency, or for general consumer purchases.

The international settlement use-case also gets around two of the traditional weaknesses of Bitcoin. The fact that it's deflationary is not concerning when used as a unit of international settlement, because national currencies can be made to be inflationary to spur consumer activity, and then just float relative to Bitcoin. And its low TPS limits also don't matter much when it's only used for general international settlement between large financial entities, rather than as a payment coin for ordinary consumer purchases.