In summary : There are three things that could happen to massively increase the odds of the Games happening.
1. An effective, safe vaccine.
2. Effective therapeutics, like the kind of thing they gave Trump
3. Cheap, accurate and fast point of care testing.
I believe that even if a vaccine isn’t widely available by the Olympics if the other two are in place, they will be game changers.
If there are tests available that they can administer 2x per day that provide independent samples then you can test people multiple times prior to competition and establish rules for isolation in case athletes test positive, rules that all athletes and coaches etc agree to abide by.
If next generation therapeutics reduce the duration and severity of the disease then the risk/reward curve changes in favor of the games.
Lastly on top of all that I feel that because the Olympics take place inside an Olympic village it’s quite different than the French Open or any other competition so far and far closer to the NBA bubble.