The Russian-Chinese "alliance" is an alignment of convenience that is running out of reasons to exist. And Russia has alienated their potential allies in the democratic world.
This observation of a rift opening sounds right to me:
Professor Alexander Lukin’s latest article in the Washington Quarterly notes this change. Back in 2018, his book “China and Russia: The New Rapprochement” discussed the promise of Sino-Russian cooperation. In contrast, Lukin now frankly admits that “any possible changes in U.S. policy will probably prove less of a deterrent to further Russian-Chinese rapprochement than will Russian concerns over China’s growing assertiveness.” He argues that “the peak of Russian-Chinese rapprochement has probably passed.” ...
Lukin’s view may represent a certain shift in the thinking of some Russian elites, who cannot voice their concerns publicly due to the necessity of maintaining the superficial harmony of Sino-Russian relations. If Lukin’s critique is correct, beneath the surface, Russian elites are worried about China.
China needed Russian military technology and Russia is running out of things to hand over that China can't do better, as I noted in this post:
China is using Russia. Have the Chinese mastered jet engine production? If so, the Russians need to worry about the day when China no longer needs to strip post-USSR Russia for high tech parts that China can't make for itself.
Although Russia had reasons to give China much of that technology in the past, now the technology can be turned against Russia.
And China has reasons to target Russia for lost territories on a large scale.
And it isn't just the Far East. The former Soviet Central Asia is at risk, too, where China will build a police base "for" Tajikistan. Is Russia's coming split with China being telegraphed in that region?
The bottom line is that Russia has been appeasing China for over twenty years. And Russia can see that Russia may have just 5 more years before it has to face China.
Could Russia possibly align with the West after its decades of threatening the West?
Russia has alienated the West which was not a military threat to Russia by pointless threats to the West given weight by Russian invasions of Georgia and Ukraine, even though the West was willing to help Russia upgrade their defense industry until 2014; while China stole and then surpassed Russian military technology and production methods.
Lukin has it backassward on causation when he argues Russia is unlikely to change policy despite understanding the threats from China:
Nevertheless, as Lukin argued, the pressure that the United States and the West are putting on Russia is far a more powerful policy motivator than China’s growing strength. Thus, in short term, Russia’s foreign policy is unlikely to change.
The West reacted--putting pressure on Russia--because Russia got loudly aggressive. It isn't the reverse. Yet in the east, Russia may find that China no longer cares if Russia accepts vassal status when Russian territory and natural resources seem ripe for domination and then liberation.
Because of their bizarre hostility, Russia may find that it will have to face China alone even though America, Japan, and South Korea have reasons to prefer a weak Russia in charge of the Russian Pacific territory.
The best case for help from the West may be a non-aggression pact in Europe that makes European Russia a safe rear area to support the distant thinly manned Russian front line in Asia.
But I admit there is a chance there is deep diplomacy going on to bring Russia in from the cold. Hopefully no administration forgets that Russia needs American and NATO friendship far more than the reverse.