I've been hearing "China is tired of Russia's shit and is about to betray and leave it on it's own" talks since the March 2022, so all of it just sounds like cope at this point.
It's all just sensational clickbait. We have to firstly question how would America fight a war against China? It would be primarily a naval affair with potential fronts in Taiwan and maybe Korea. This is assuming Russia would not get involved, the conflict as such would be primarily naval. It would be near impossible for a land invasion to be launched against either China and America and it would be a practically unwinnable affair for either side and would be determined by how much one can damage the others economy. China's agenda is thus to help secure resources and maintain significant trade influence so that they can maintain a global position in the event of conflict. Practically everyone would acknowledge US international naval supremacy but the navy isn't everything.
The Russian dilemma is one primarily based around these variables:
- The ability to use Russia as a means to trade with Europe.
- Is Russia beneficial for their African policy?
- To what extent does the war in Ukraine damage the western opposition to China?
- How much can China influence Russia?
The ability to trade with Europe is not important if Europe is an ally of the US, thus China's policy has to firstly assure they can have positive relations with Europe that supersede that of their relations with the US. They've been partially trying to befriend Europe but the US still maintains significant influence. Russia's war in Ukraine is irrelevant UNTIL Europe would prefer China to Russia. At this point, the question then becomes how effective of a route to Europe will Russia be?
Likewise, in many ways Russia and China have a similar agenda in Africa, Wagner whether you like them or not is a useful tool in Africa concurrently for Russia. If both Russian hard power and Chinese soft power work in a combined grand strategy then that is useful for China. With Niger for example, this is a country that France had significant interest in and was a geopolitical loss for France with it also weaking their sphere of influence over West Africa. If this collapses then the continent could then be brought under further Russian and Chinese influence.
Ammunition used by the navy is different to that used by the army, other industrial factors need to be understood in how precisely a war between America and China would be fought. Missiles will be important because of the duration needed for ships to be constructed with this being more desirable for China which as a country will be more boxed in as at the imminent outbreak of war they'll likely be up against part of the US and Royal Navy, the Australian Navy. South Korea and Japan will also be of the main bulwarks. Russia again isn't really that important. There are only few areas that may be directly relevant such as that of ammunition that can be used at range to be able to target ships or China proper. This is primarily why the west has sent older weapons instead of decommissioning them as they are not relevant in a war against China. Those weapon systems were primarily envisioned to be used against Russia in the cold war which from a doctrinal stance it means they are more likely envisioned to be tailored towards fighting Russia.
A weakened Russia with the ability to project power is the best result for China. By all metrics, War is typically bad for countries and China is aware of this and they can use this to get further access to Russian resources. China doesn't need to conquer Siberia to exploit Siberia, all they need to do is to groom Russia. Russia of course isn't naturally going to capitulate to China but if this viewed as beneficial to China then they'll begrudgingly accept it. By cutting off Russia from the liberal international order, what the west did is pushed them to China and we've seen this from developments of gas pipelines to China. They have a common agenda of working towards a multipolar world and they'll likely continue to work together in this role given other alignments.
So no, China is not going to "betray" Russia as from a rational point of view it is not in their best interests. Russia retains resources and influence abroad which is useful for China; Countries are rational creatures that aim to make choices in an anarchic international world. Countries make friends based around their policy agendas. China understands that it needs friends and has been gathering them. A Taiwan war won't include Russia directly and the Ukraine war doesn't include China.