It seems like the timeline for reopening theme parks should also depend a lot on what precautions they are willing to take. If the parks agree to slash capacity, conduct temp checks, require masks, offer lots of hand sanitizer, encourage spacing between groups in queues, skip packing people into small preshow rooms, leave empty seats between parties on ride vehicles, frequently sanitize rides, end meet and greets, require space between groups in show theaters, and prevent crowds from forming at park entrances or food service locations, then a reopening around the July timeframe is probably a lot more reasonable than if they refuse to degrade the experience so much and wait for a later reopening.
I'd imagine that a similar argument could be made for sporting events and concerts by only selling like every fourth seat to leave space and limit capacity.