It seems to me that the West might have lucked out with the Sino-Soviet split in 1960. I've read some of the reasons for this but I'm still surprised that the USSR and China, despite having mutual foes and more in common than not, still decided to bicker between each other rather than work to a common cause.
The was concern that China is heading down the path of become Soviet client state, which is not the role China want to play. How China reacted when USSR asked for basing rights was a good indication of this. Additionally, hunguaian Uprising of 1956 clearly indicated to the Chinese leaders Soviet Union will not be a equal partner. (If read the memoir of Chinese leaders from this period, these two event are a yurnig poit for them) Additionally, Russia and China had bad blood from before, and border disputes still carry into the Soviet days, and was always a point of contension. (They are only resolved in 1991) Lastly, United States is far away from China and had limited desires on China itself or its internal politics. Soviet Union, however, is close to China and has shown interest in China before and has meddles with CCP on mulitiple occations Will USSR backs a faction in CCP(see previous link) and get rid of existing leaders. One can certainly imagine it.