If Pujin will fall from power, Xi will be the first man at the table to chop, chop Russia. Even back in Jiang years, people in BJ were mesmerised at the ease with which Russian governors were ready to fell to their feet for completely laughable sums. It was actually BJ itself which put a stop to our compradors getting too enthusiastic with that.
Since 2007, a Chinese person, or a company can't own foreign land through any kind of direct deal with a foreign government.
Possible fall of Russia will be both an huge boon, and a headache to Beijing. The value of Russia distracting NATO militarily is slowly diminishing in comparison to potential profits from Moscow loosing hold of its natural resources in Russia, and its satellite states.
Eventually, NATO will ignore Russia even if they will grab 1 or 2 NATO members just because USA wants to obsess over China so much. Having Americans on the norther border in this context will not make much difference because they are already all around us in Korea, Japan, TW, and now across Himalayas.