A few notes:
On attendance/crowds: I want to emphasize that there is no evidence that demand is going up significantly. In the current moment, higher crowds does not necessarily mean higher. I'd argue that the current demand was already there back in July, but just wasn't being met with anything close to the adequate supply. How do I know this? Because 1) these increases in attendance have correlated with Disney releasing more and more AP spots (and as they release more, they have to take more from another bucket, which is why you see the Theme Park Ticketholder bucket now has a little less availability) 2) hotel occupancy rates (on property and especially off property) aren't even close to where Disney wants them to be, and 3) the drop-off from weekend attendance to weekday attendance is still significant, far too significant relative to where WDW wants it to be. WDW doesn't just make money on its theme parks. Its revenue model is one that is designed to capture as much business as possible from Guests at almost every point of purchase throughout a weeklong vacation. When Chapek said that AP holders don't spend as much as a 5-7 day resort guests, that's what he was talking about. The average AP holder (who doesn't do an extended resort stay) doesn't visit enough days to make up for the revenue they would get outside of the parks 24/7 for a week. People underestimate just how much that is. Even if food and merchandise are making some money in the parks, resorts, resort merchandise, resort dining, bars/lounges, add-ons are all seeing very, very limited revenue. Remember, from the poll a few weeks ago, that just over 3/4 of Americans don't feel comfortable visiting a theme park at the moment. Labor Day shows some hope, but after that, September is going to be very rough. All eyes are on October now. That's the month that will determine what the rest of 2020 and early 2021 looks like.
On park hours: Remember that the hours are a template in a way. If they really start seeing demand pick up heavily in October, they can always extend hours on certain days. It's a lot easier to do that than to cut hours on short notice. After these hours reductions, I wouldn't be surprised if the next step sees them increasing hours on weekends and leaving the reduced hours in place on weekdays. This wouldn't happen until after September at the earliest and that's not to say it will happen. Prior to the closure, WDW extended hours all the time and it was very common to see one set of hours for the weekdays and another set from the weekends (i.e. S-Th MK open from 9am to 10pm, F-S MK open from 9am to 11pm). That said, there are still so many unknowns here. I'd caution against lending any credence to anyone (including posters here) who try to tell you something about what will happen with this pandemic with any certainty. Nobody knows and anything can happen, so there's no use in trying to derive a false sense of reassurance from someone on here.
On holidays: As has been discussed, there will be holiday decorations up this year. The details of what festivities will be offered/cancelled should be announced soon. I know there's been quite a bit more activity in Holiday Services since we last broached this topic, though not as much as a regular year.
On the 50th: As Ryan and others mentioned, the original (pre-COVID-19) plan was to start the festivities sometime just before summer (think how
Disneyland's 50th started on May 5 and its 60th on May 22) and continue well into 2022. Of course, the plans have changed. Last I heard (which was back in early April, so it's very possible that things may have changed), the plan was to push the start date to October (to the actual fiftieth) and run it through the very end of 2022. That way the projects should hopefully be done by that point and the hope was to be able to mostly finish the trimmed down Epcot redo by then as well. Nobody knows what 2021 holds, including Disney. The hope is obviously we get a vaccine and/or a therapeutic, but based on everything we're hearing, even if the U.S. has an approved vaccine by the end of this year, we won't have distributed it and then built up enough overall immunity in any meaningful way until probably late Spring or summer at least. Now, when WHO says the pandemic won't over for two years, remember that they're talking about the global situation (not just the U.S.) and there are lots of different countries with all sorts of different resources and unique situations that might affect their response, vaccine availability, and community spread/immunity. I'd argue that most of the current WDW restrictions will have been relaxed before the global pandemic is declared over (that's not to say they're going away anytime soon). The threshold for that seems to be very high.