Did the ATP give any thoughts to perhaps scheduling Toronto & Cincy a week later this year? Although this would have not been the perfect solution & participation at Cincy may have suffered somewhat as a result, it would surely be better than the mass exodus we are witnessing now.
scheduling Cinci the week before the US Open would have led to a more massive exodus, I think.
The ATP had no other choice if one thinks carefully, considering that they have no weight in the decision in the dates of the Olympic Games.
This is particularly unfair to a player like Djokovic who is defending 1000 pts in the Rogers Cup and will now probably have to W/D or tank to avoid physical injury/exhaustion.
the notion of "defending" points only has a signification in a case of a player who has a massive advantage on one surface like Nadal on clay.
Beside that, I don't use this notion like that : the points from last year are lost 52 weeks later anyway then everything starts from zero and you do your best in every tournament. That's the way I see it.
Djokovic and Fed will be top-2 seeds in the US Open anyway
Besides, I don't think Djokovic will withdraw : he lost his double in first round in 2 sets and didn't have very tough matches, the Olympics are not tiring at all for him so far
I can see Federer (old) and even Murray (used to not being interested in other tournaments than slams and Olympics recently and still in mixed doubles) withdrawing much more than Djokovic withdrawing.