When do we think that the tourism industry will recover from this? In a year or less? Or are we talking multiple years, or maybe even decades in a worst case scenario?
Multiple years, for sure. The lockdown could last through the summer, at which point seasonal parks wouldn't even bother to hire and train temporary workers for the remaining weeks of the season.
Long story short, what determines how quickly a country could let the epidemic burn through it is how many intensive care hospital beds it has. For most of the developed world, that's around 100-200 per million inhabitants. Assume only 1% of those infected need intensive care, that means around 10-20,000 people per million can carry the virus at any given time to avoid disaster. That's 1-2 % of the population. Assume that everyone takes two weeks to get through the illness, and that the epidemic burns out when 70% of the population has had the illness and become immune. That gives 35-70 weeks before this blows over. Any faster, and you'd get more people requiring intensive care than the healthcare system can deliver at the same time, and the governments out there will pull all the stops to prevent that from happening.
By then, effective treatments or even vaccines might be available, but it'll take a long time to roll it out to all who need it. So I'd expect the tourism industry to be locked down for at least a year across most of the world. 2020 will probably be a write-off for most parks out there. Time will tell if everybody has the financial capacity to open next year, and what the public apetite for large gatherings will be by then. If we're really lucky, attendance might be back to 2019 levels in 2022 or 2023.