I don't know, China is a civilization masquerading as a country, I don't know how much use asking questions like this is about such a massive thing, that time has probably already come in some ways, is yet to come in others and yet still other ways that time has been thwarted decisively from coming to pass.

From a zoomed out perspective the two things that matter the most are how genuinely China embraces green energy as it continues to industrialize (again a very complicated question full of hyprocrisies and contraditions as these things are) and how much China can continue to elevate the quality of life of its people.

China is such a massive country with such a long history, I am not sure how much it is worth focusing on your question because even if you knew when it would happen, in order to predict what the consequences would be in terms of domestic shifts in power within China and how they would influence the rest of the world you would have to entirely be focused on following the minutae of Chinese politics and the obscured power dynamics going on to the exclusion of following anythign else.

I think the most important thing to do here is treat China as an empire, not like some new powerful dragon to understand, but a boring old empire that has joined the ranks of other empires. Yes China is notable in some of the ways it has done this without batshit crazy european style colonialism, mass genocide across the world and chattel slavery... but that doesn't mean China isn't an empire as this article lays out.

The structure of empire is the problem, and it is like a zombie that can arise out of any set of starting conditions, there is nothing truly unique to a place that becomes the center of an empire, which isn't to excuse the choices along the way but rather to frame them in their proper boring context.

That all being said as someone from the US it is virtually impossible for me to establish the ways in which China behaves as an empire in any kind of objective way because my own society is so hellbent on silencing conversation about how much the US and European countries are behaving like empires by pointing at a fear of China doing those things.

Yes I don't want China to do the things we are doing right now, we should be wary of China doing them. Also can we stop doing these things ourselves!?... and why does everyone always rush to bring up how China is doing the same thing but worse when I try to make a point about how we should stop doing something bad? Whether I agree or disagree it is frustrating all the same.