The China-Russia border thing is an interesting one; the Chinese believe that they were unfairly screwed out of Siberia by the Treaty of Nerchinsk and a couple of following treaties; they are generally as upset about this as they are about Taiwan but it goes little noticed in the West.
The primary reason why Russians are upgrading their nuclear arsenal. You get a few million Chinese to invade Russian east, and whoop! There's the solution for the Chinese overpopulation. Except I doubt the Russians would target the "backwater". Ahh, nuclear weapons. The great equalizers. Russians know they cannot contain China through conventional means. The problem will only grow. A nice little limited exchange (limited, since china has only limited stocks of warheads) would certainly consign the Chinese to the trash heap.
I agree, and this has been slowly unfolding for awhile. The first I ever heard of it was a Stratfor report called "Russian Far East Turning Chinese?", which is available here . Just four years after those predictions were made The Globe and Mail reports about the rise of Chinese influence in the region. It definitely bears watching.
Maybe we could make a deal with China...they can have back the land they lost to Russia in the 19th century, in return for letting the future of Taiwan being decided by a vote of the residents (independence, immediate incorporation into Red China, or delayed incorporation into Red China).