One thing I have thought about is whether any theme parks will extend their season, possibly to the end of November. Would that help theme parks in terms of having another 3/4 weeks to make money (obviously only a small percentage of what's been missed out on in the first half of the season)?
The reason why parks aren't already open at those times of year is because demand tends to be rather low even in normal times. People will want to go out and about after being quarantined for months, sure, but they probably would explore other options than going to a theme park and paying the high entrance fees to freeze their buttocks off on a coaster on a rainy November day. I think that if parks have to wait until August to open, many will simply choose to stay closed for the rest of the year. Hiring staff is expensive (not just paying them, but the hiring process too), stocking the shops is expensive, inspecting rides and approving them to open for the season is expensive, cleaning and maintenance is expensive, marketing is expensive, printing park maps is a cost too - in short, every season requires a lot of costs that will only be earned back after weeks of operating. If the park can't guarantee enough traffic to pay for those costs before the season ends, they will be better off not operating at all that year. Just stay in off-season mode until next spring, rather than paying to get it all up and running for a short couple of months.
Another thought springs to mind, though: what happens to a park that goes bust? Say for instance that a park declares bankruptcy after a horribly bad season. The physical park would still be there, with all its infrastructure, rides in place and working, building regulations, transport links, public image, and so on. Wouldn't a new owner usually be able to take over, if there usually is a market for the park to operate? I don't think it would always pay off to dismantle the rides, sell what can be sold, and turn the land into a housing development. Sometimes the creditors would clearly be better off by selling the park wholesale.
The question then becomes what a new owner would be able to do. Say the current owners of a park are heavily indebted. The creditors would then take over and sell off the park to some aspiring entrepreneur out there. The new owner wouldn't carry the debt of the old ones, would they? I mean, they would probably have to borrow a lot to afford the park, but at this point the old debt would have to be erased (otherwise, the park might have a negative value, in which case, who would want to buy it?). The new owner wouldn't be in the swamp of debt and bad credit rating the old owners were, and might have the opportunity to borrow a little extra and put in a new attraction or two, a possibility not afforded by the old owners.
So I'm not saying I'm fully optimistic here, but I think a park going bust wouldn't necessarily be a bad thing for its visitors. Revitalization previously thought impossible (hi, LWV!) might become a reality under a new ownership situation.