Yeah, but that's one hour from never. Russia desperately needs the US around to keep China in check. China has designs on Russia's land mass, and Russia knows it. Russia's population is shrinking, China's is bulging at the seams.
If they took out the US, the very next thing to happen would be a Chinese invasion of Russia, and there wouldn't be a whole lot Russia could do about it.
If Russia were to join up w/ China, it would be a dance where the they follow, not one where they lead...