I'd say low. What's the minimum number of fans that makes it worth it? Considering fans require security, parking, ticketing, first responders, probably a few people to sell or provide water. Depending on protocol, other stuff like buying hand sanitizer, bringing in people to do temperature checks. Teams probably getting a break on their insurance that they'd lose. At the end of the day, for opening the park to fans make financial sense you're probably getting the point where capacity needs to get to levels few teams or their local governments are going to accept within the next six weeks or so.