How long until China looks at all the Russian Land as easy to take?

Russia is supposedly a friend to China, but really China needs more land. Why fight and loose a million people over Taiwan and risk nuclear war, when they could invade Russia instead. Crossing a land border. There would be no help from the West for Russia at this point, and China would win easily. A massive land grab with no boundaries.
Take out the nuclear bunkers on one massive attack and then move your recliners in.