That's not entirely true. They could still do a TV broadcast with elites-only which will reduce their losses versus running nothing I'd imagine.
I could see them doing some kind of "top 1,000 , Americans-only" kind of race if they check your temperature and give you a quick corona test in the athlete village (assuming that would be a thing by September). Would be easier to contact trace those people. No crowds at the finish line, but allow people to socially distance and cheer along the course in the outer towns. Maybe make the course narrower to ensure no spectator can get within 10 ft of a runner?
Idk just trying to come up with what the best scenario would be from the BAA's perspective, cuz there is pretty much no chance 30,000 runners and 500k spectators are gonna be allowed to participate in this thing.