Property rights and such are secondary. The primary issue is: who has the power? Right now the answer to that question is "US", but since China is catching up on GDP, and, unlike US, actually manufactures things. If China decides that they want payments for all the goods that they export to be in RMB then there's nothing the rest of the world can do about it, except stop all the imports from China (which would take decades, because they have to learn to manufacture all those goods themselves). Once most of your imports come from China instead of the US it does make sense to use Chinese currency as the reserve currency, since you are going to need a lot of RMB to pay for your imports anyway.