I think it will be interesting to see what the parks will be like for my trip in two weeks. I went recently after Thanksgiving (arriving Friday night) and the weekend was quite busy, but the weekdays were pretty slow, even though everyone was saying the first week of December would be busier than usual since resorts sold out super early and RotR, etc. We experienced HS wall to wall on Sunday and MK wall to wall on the one night it was open late, but otherwise some days the parks felt empty. FoP was 65 min almost all day on our AK day (even with sun and blue skies).
One thing I thought was interesting was how drastically different the crowds were in different parks. On the Saturday after Thanksgiving we did Epcot, which felt extremely moderate in terms of crowds. Lots of open walkways, good FP availability, pleasant in general. Maybe a 4/10 to me. We went to HS briefly and it was wall to wall, honestly unbearable. We lasted maybe an hour before going back to Epcot for the rest of the evening. I would have put HS a 9/10 (avoid at all costs).
Same thing happened on our AK day, like I said it was empty and we literally walked down pathways and there would be no one in sight ahead of us. I saw three different FoP fast passes while refreshing in the afternoon. Safari FPs were immediately available even after lunch. We went to MK in the evening and again it was wall to wall (more due to HEA having a rare showing plus evening EMH, a rarity during
MVMCP season). It was such a drastic difference. So even if one park might be terribly busy it doesn't mean WDW as a whole is, that's why I will never go without park hoppers. Get your 3 FPs in and switch parks if need be. We would have been miserable if we were stuck in a busy park all day, especially if we looked at wait times and saw other parks that were empty.