A well-reasoned summary.
You emphasized the economic and political implications of oil, and there's a lot of reasons why that's a smart move. But I'll point out that an awful lot of Russia's oil reserves are Siberian. Though nobody is saying it out loud, China covets Siberia; strategically, it would catapult them into a completely new geopolitical and economic reality if they could ever get their hands on it. Russia realizes this. It will never fully trust China.
China plays a very long game. Not for them the focus on quarterly profit reports or elections every two years.
Russia has a habit of imploding every few decades. When it does, we're reminded that Russia is a troubled empire, not a nation. The breakup of the USSR was a start towards empire dissolution, but it won't be finished until Russia itself flies apart, too. Russia is made up of extremely diverse cultural and ethnic groups and is rife with internal pressures; that's one reason it's tending to lapse back to authoritarianism, it's the main thing that keeps the lid on and lets people go about their daily lives.
Russia also tends to need a belligerent foreign policy; external threats help to keep the empire together. The dissolution of the USSR was at least partly due to the gradual realization, despite internal propaganda, that nobody was really threatening its land mass militarily. Pretending otherwise was bankrupting it; they had to drop the pretense. Now that it's doing a little better economically, Putin finds it politically expedient to turn up the belligerent rhetoric a few notches, rebuild some of its lost military capability, and manufacture a few incidents. He won't want to go so far as to provoke a serious Western response, probably. But some tension serves his purposes.
If China does hunger for Siberia, what strategy would it use? Here are some ideas.
1. Take the US off the board, somehow. Tie it down with indispensable economic ties, build a closer relationship, be seen as unthreatening to US and European interests. Follow the Japanese in buying up as much of America as possible. Employ lobbyists; buy America's eminently corruptible politicians. (And don't get caught painting children's toys with lead paint, or spiking food or toothpaste exports with toxins. Oops.)
2. Displace Siberians with Chinese nationals, illegally if necessary. Build a majority population there, but keep a very low, nonthreatening profile.
3. Wait. When Russia implodes again, mobilize and seize Siberia "to protect the ethnic Chinese majority." For that, China will need to modernize its military forces and train them well, especially in logistics. Humping artillery shells on human backs over the mountains might have worked in Korea. It won't work in Siberia, it's just too damned big.
4. No need to sit on their hands waiting, though. Covert encouragement of Russian minorities and factions to tear at each other could speed things along. Russia will adopt a belligerent foreign policy with the West all by itself; a little covert prodding and it might start to look serious. Get it right, and a Chinese takeover of Siberia during a Russian implosion might even be hailed in the West as a welcome development.
Empires made up of ethnic regions dreaming nationalistic dreams don't last forever. They are not sufficiently politically stable for it. A few centuries is about the most you can hope for. Russia may well be nearing the end of its useful life as an empire. It probably won't fall apart soon, but the Chinese are a patient people.
Acquiring sparsely populated, resources-rich Siberia is truly the boldest, most profitable thing that could happen to China. Perhaps they won't do it. But you can be sure they're thinking about it.
