I think 2026 will be the year China has to decide what it wants to do with Russia. Prior to this China was gaining significantly from sales to Russia of non-military and dual use products when eventually made it into Russian military supply chains through vast networks of brokers from Kazakhstan to Türkiye. Additionally China was able to take payment in oil and refined petroleum products negating global SWIFT restrictions imposed by sanctions.

Three things have change in December of 2025:

Kazakhstan has now imposed strict controls on exports of dual use products to Russia via Kazak transport networks. This doesn't mean that dual use products will never find a way to Russia, but instead they'll have to resort to smuggling which is far less reliable and far more expensive to Russia. This is a major chokepoint for Russian logistics, but also means easy and consistent sales from China are now bottle-necked. The result is China will be moving far fewer goods to Russia.
The Russian shadow fleet, has been targeted by Ukrainian special operators and drone pilots resulting in the loss of a number of tankers. Additionally the USA has seized a number of vessels through port in Venezuela which also served part of the shadow fleet network. The result of both of these things is that insurance costs have skyrocketed. Vessel and crew availability has plummeted. Crews are refusing to take on Russian shadow fleet work for fear of being blown up by Ukraine or seized by the USA. So this means China can't get paid for any sales to Russia in any currency it cares about (oil) beyond a trickle through other means.
Russia has pissed off Türkiye with consistent drone incursions into the nation. This is not good for Russia. Not only is Russia dependent upon Türkiye for avoiding sanctions, but also for regular access to the Black Sea through the Bosphorus Strait. While Türkiye has already restricted Russian military vessels transit years ago, it still regularly allows for Russian civilian/merchant traffic under the Montreux Convention rules. However, there are substantiated claims that Russia has been outfitting tankers in disguise. These tankers can containing drone launching platforms and carry GRU agents to perform asymmetric operations against NATO countries such as disrupting civilian air traffic. With the drone incursion, this might be enough for Türkiye to decide that even civilian tankers are military and deny them access to enter or leave the Black Sea. Just this week Türkiye scrambled a Turkish F-16 and shot down a Russian drone approaching the Türkiye coast. This is a shift in behavior from Türkiye in the past.

Where will Russia go when it has pissed off these vital intermediaries it absolutely depends on to continue the invasion in Ukraine?