I was pretty optimistic that the parks would be open 1st June, on the basis of how the virus is peaking in both Europe, and also the USA as a whole. I am a safety, risk and statistic expert, and I've been doing quite a lot of number crunching on the figures coming out of various regions, and initially, Florida looked like it was following the trends from other regions. But my latest analysis of data seems to indicate that Florida is being pretty successful in flattening the curve, which will push out the peak date somewhat. So I have now changed my opinion, and think that there is a reducing chance of the parks being open 1st June - I would say that a 1st July date is more likely. We arrive 6th July, so I would place the chances of our trip going ahead no better than 50/50 at the moment.
Even if it does open by the time of our holiday, I'm worried what the experience will be like. The cancellation of the CP does worry me - does this mean that one of the parks might need to close? If so, that could be enough for us to postpone our trip. This is likely to be the last trip we make to WDW as a family, and with the amount we are paying for the trip, we don't really want to it to be compromised on quality. A closure of any of MK, AK, or DHS would be enough for us to cancel, as we want to experience the newer rides that are there since our last visit. EPCOT we could possibly cope without - not much new there at the moment, and the construction going on makes it less appealing. I could see some benefit for Disney in keeping EPCOT closed a bit longer - it would allow them to get on with the construction work much more easily. However the lost revenue from the restaurants might be an issue. But closing a main park would potentially make crowds in the other parks worse. So my gut feeling is that if the parks open, all will open at once, to spread out crowds.
However, I can easily see Disney closing one of the water parks - and closing one of those isn't a deal breaker for us. Likewise other stuff like miniature golf. Individual restaurants or food kiosks might well be closed as well - numbers are likely to be lower than usual (I can't see a flood of people coming in the first few weeks the parks open back up).
But for foreign visitors, it won't just be what is going on at Disney - I'm from the UK, and whether Universal, SeaWorld and Discovery Cove are open as well will factor into our decision - if they aren't, then even if Disney is fully open, we will postpone the trip until next year. However, I suspect all the parks will try to co-ordinate opening, because if they don't, the first park to open is just going to get flooded with guests. One way around this is to limit attendance to resort guests only at WDW - that would be nice for us, as we are staying on-site. But that could end up with more crowds going to the other Orlando parks - so I think it would be better not to do that, for the greater good of Orlando tourism.