Sports will likely be viewed as something that can be put on hold. Unless they figure out a way to support sports without fans, I'd be surprised if they happen.
I just don't see a lot of fan attendance across the nation if no vaccine/immunization is available. Same with movie theaters, music concerts, passenger flights. Anywhere large groups of people are in close proximity or an enclosed area. I think there will be a lot of apprehension for a while from Americans in general about grouping up if they don't have to.