Oh yes, there has been comparisions to the 1936 Olympics in Berlin. Big difference is that there is going to be 21st century hightech glare of exposure.
I think that the kind of Olympics that you might get might be more comparable to Mexico City 1968. Those were the “party hard” games and the “Black Power” protest games. You could see a spontaneous replay of Tienanmen type protests over Tibet, Darfur — or whathaveyou. China would be faced with a choice of allowing the demonstrations, or pulling the TV/Internet plug on the whole thing while sealing the Olympic Village & cracking down on the organizers.
I don’t think the Jesse Owens ‘36 example is good even though the Han Chinese might consider themselves racially superior to other Asians. It just wouldn’t register much outside the region — unless the Japanese or South Koreans come up really BIG — that might be embarrasing for China.