I've understood the subject.
So that new reserve currency would be pretty much like gold. But no currency is pegged to gold any longer, and you may say that all national currencies are currently floating against gold, or that gold floats against each national currency, but few countries will accept that this new reserve currency shall be the standard against which all the others should be measured. Setting a reserve currency requires a consensus to begin with, but that doesn't exist at this time. Questions to ask is what authority could say this is the new world reserve currency, and why should countries accept it as such.
This topic should not be in "Economics", but in "Politics".
I agree. No world authorities are going to agree to such a thing; it's in nobody's interest to do so. The IMF has been trying to push SDRs for years now with the biggest problem being that countries have to deal with the IMF and become a member. The stipulations are way to grand for it to work.
The next reserve currency (if there is another one) would do best to be backed by something infinite, easily obtainable and liquid. Finite commodities like gold or oil end up one-sided and serve the good of those who hold the most.