Fair, USSR has greatly advanced the cause of socialism while it was around. However, I don't see how you can say that China hasn't advanced anything since the days of USSR. For example, the pink tide happening in Latin America is directly facilitated by trade with China.

If China falls, the world will likely regress, but the march towards socialism will not stop. Ultimately, it's the inherent contradictions within the capitalist system itself that lead to its ultimate distraction. In my view, the most important task today is to break apart US led hegemony over the world. Global socialism will not be possible as long as US empire remains dominant. It seems to me that China stands a very good chance of achieving that with its current approach.