200 years from now, the border between Russian and China will be the Ural mountains (if Russia is lucky). According to an article in the American Thinker in June 2005:

"The temptation to seize the Russian Far East and Siberia may be too much for China to resist, since the region would offer the country an opportunity to achieve increased energy autonomy and replace its own depleted natural resources. Many coal mines in China are nearly exhausted, with further exploration an expensive and time consuming alternative. China also imports more oil than it produces—a significant barrier for a country of its size with designs for regional dominance and global influence.

The article continues:

"China could decide to take conventional military action, embarking on its own “Chinese Blitzkrieg” to secure the Russian Far East and Siberia. Such a large-scale invasion would almost certainly elicit a nuclear response from Moscow. This is something both countries would want to avoid, since any large-scale nuclear exchange would all but destroy the area’s natural resources, not to mention other obvious drawbacks. Although weakened by the breakup of the Soviet Union, Russia’s conventional forces remain formidable, capable of confronting any Chinese aggression.

One must question whether Russia's conventional forces are in fact "formidable" where China is concerned. China could easily thrust 2 million or more soldiers into Russia's Far East, and Russia has nothing like the capacity field that many troops, much less project them quickly from bases in the West toward China. After all, Russia still can't even subdue tiny Chechnya, which doesn't even have a regular army. Moreover, one must question whether Russia could possibly fire nukes at China, since Chinese retaliation could affect Europe, without NATO approval that it would never receive, and whether Russia could risk a Chinese response that could erase Moscow and St. Petersburg.

What's more, as the article notes, the issue of population is key:

"Vladimir Yakovlev, Russia’s regional Asian development director, recently commented that Russia’s total population had fallen to 145 million – a decline of 1.7 million people over the past two years. If the Russian population continues to decline at the current rate, some experts estimate it could drop to 100 million by 2050. Despite draconian population control measures, the Chinese population continues to increase, placing rising pressure on Beijing to find open space. Even a very slow increase from a baseline well over a billion souls provides a lot of new people.

Thus, China can take the Far East without firing a shot:

China could adopt a policy of 'gradual assimilation' and 'soft influence.' Under this scenario, Beijing would sponsor increased migration, hoping that the Russian-Chinese population would eventually be capable of exerting influence over regional politics and thinking. Beijing could then use this opportunity to question many of the boarder treaties now in place, demanding concessions from Moscow."

Russia would be even more helpless against this option, since the only way it could be resisted would be in concert with NATO, which Russia has already alienated by supporting Iran and Hamas and fighting the incorporation of the former Soviet slave states into Europe. In fact, population would be crucial in a nuclear exchange as well. If Russia lost 20 million people in Moscow and Piter as the result of a Chinese assault, that would be 20% of Russia's population. If China lost 50 million to Russian ICBM's, more than twice as many, that would still only be a tiny 5% of China's teeming population.

The conclusion is obvious: Russia will lose Siberia the same way it lost its Tsar and its Politburo. Implosion.