Russia never worked very well. It didn't work under the tsars, it made some progress under communism but never caught up, it regressed when the USSR broke up and Russia tried capitalism (deaths and poverty rose a lot), the oligarch era didn't help, and it's not doing that great as a semi-dictatorship. Containing the USSR worked because nobody wanted the USSR in charge.
China, on the other hand, has a system which is moving forward rapidly. It took them a long time to find something that worked. They had their disasters, such as the "Great Leap Forward", under Mao. Now, though, the country is doing a lot of things right. The government is unapologetically authoritarian, but not stupid. As long as the government can keep the standard of living going up, it can stay in power.
China's foreign policy is another matter. The government would like to dominate Asia. Taiwan remains an annoyance, but it's more like Cuba being an annoyance to the US, not a real problem for China. The countries in the area spend a lot of time and effort fussing over minor islands, but that's not likely to lead to a major war.
China is gradually building up a blue-water navy. With the amount of shipping China has, that makes sense for them. China has a lot of economic interests outside China now, and wants to be able to protect them. Economic power, not military power, leads the way.
It all depends on whether China can maintain its growth rate.