Russia always feared China, even when it was militarily stronger. The conventional military balance is already in China's favor, shifting evermore so as time goes on. China and Russia might have short-term partnerships of convenience, but in the long-run, centrifugal forces are greater than centripetal ones, and whatever alliances the two conjure wouldn't last any longer than the defunct Sino-Soviet pact.
Oh yes the feared "Yellow Peril", Russia is soooooo afraid and suspicious of China's growing military strength that's why they've been supplying China with advanced SAMS, advanced missiles, fighter aircraft, jet engines, military technical cooperation, etc. for the past 15 years, because that's Russia signal that Sino-Russian relations are still bad lol...it's America's "White Man's Burden" and duty, to save Russia from the "Yellow Peril", just like from a Tom Clancy novel lol! And I'm sure China's strategy to Invade Siberia by 2030 is to make itself as dependent as possible with fighter engines and other possible Sino-Russian military technical cooperation, as well as LNG, nuclear, crude oil cooperation...because we all know those strategically important trade/goods being cut off would not hinder and invasion strategy attempt by the Yellow Peril. Let's take off our "Yellow Peril" fetishism tunnel vision glasses off and address things from an empirical point of view:
1.) By the 80's Sino-Soviet relations started to heal and normalize. By the 90's Soviet/Russian economy imploded, and one of the Russian's strategically important industries was it's military technical engineering sector, which was on the brink of collapsing but was saved by foreign orders, partly from India, but mostly from China. This was mutually beneficial military technical cooperation, it allowed China to gain experience and close the gaps in quite a few military strategic fields (such as advance jam-resistance long range SAMs, Medium range SAM's, SHORAD, as wells anti-ship missiles, air superiority fighters), while preventing the Russian military industry from completely dying and maintaining jobs. China gained militarily from such technical cooperation, Russia gained military as well as economically from said cooperation.
2.) Invading Siberia for it's natural resources is orders of magnitude more expensive in financial terms and human life, compared to peacefully cooperation in investing in Siberia, which China is already doing. Russia is even actively encouraging China, which China is aptly obliging. This way is way easier and ten's of thousands of times cheaper than waging a disastrous multi-trillion Dollar invasion campaign in to Siberia that would leave a lot of major Chinese cities like Beijing, Shanghai, Shenzen in to smoldering, gamma radiation riddled craters. An as already mentioned, with all the military technical cooperation, energy cooperation, wouldn't that actually hamper the success of an invasion of such things were to be compromised? With a $270 billion crude oil contract in 2013, and a $400 billion LNG contract in 2014...do you really think China would invest over half trillion Dollars in a country they planned on bombing in to smithereens? The thought of such an event is patently absurd!
3.) All borders issues with Russia and China were settled in 2004, where Vladimir Putin publicly declared Sino-Russian relations the best they ever been. China can't launch a campaign over borders issues now, it's a bit-late for that, by at least 10 years lol!