The popular theory is that all they have to do is walk in and take it over at the opportune time.
The reality is a bit more complicated. The Siberian Russians are much more independent thinking, hearty and capitalist lot than their cousins to the west. Throw in the growing Mongol populations sitting right between China and Russia who share many of the same traits and I think you have the potential for an interesting mix: a highly independent thinking multicultural nation of Han, Mongol and Russians which can't easily be controlled by Beijing, Moscow or even the closest capital of Ulan Bator.
Don’t know if it is true, but have heard that Siberia and the Russian East have as many illegal Chinese immigrants as California has illegal Mexicans.
Yep, it’s hard to project even decades ahead, much less centuries.