Remember this is just a prediction.  I have a hard time believing that, even if the IMF decides for whatever reason to add the yuan into its Special Drawing Rights basket (thus making it "officially" a reserve currency,) this will be anything close to earth shattering, on the ground.

Investor trust is the real criterion.  If you think the US has printed and borrowed too much money, you haven't seen China.  The huge pile of official dollar reserves is impressive, but all those dollars are backing yuans already issued, much of it at a much higher rate of yuans per dollar than today.  The economy is simply flooded with money and debt.  (There is a reason Chinese citizens like gold and Bitcoin!)

It's true that a lot of this capital is controlled by the state, so capital flight can be controlled more easily.  But that's also part of the problem, since state capital tends to slow down growth, and growth is the only thing that can really cure financial pollution.

People like the greenback, sterling, euro and yen because they can get out of them easily.  For this reason the issuers of these currencies also tend to be careful not to create too much money and debt.  (The financial pollution is evident only looking across decades.)  Yuan transactions are under all kinds of state control, and there's no telling when the Chinese Communist Party will decide to issue a massive amount of assets to save its own skin.

Ultimately, finance and money are a highly political issue, despite all the economic spin that the elites put out to justify this or that action.  The yuan's problem is that it's dictatorship money.