Holiday hours at Disney can and most likely will extend as late as intra-week.
Went the last 10 years, typically:
- MK will open at 7am for EMH; 8AM to public most days. Will close around midnight or 1am; with a late-night EMH on 12/30. This is when they do the big fireworks "dress rehearsal" for NYE.
- DHS will probably add extra hours with the crowds. I wanna say it typically opens at 8am, with a few 7am EMH scattered throughout. I don't remember much nighttime EMH's, though.
- Epcot will be a lot of the same as DHS. If I remember correctly, it typically opens around 8 or 9am. When it opens at 9, there should be morning EMH.
- Same with AK ^
Years ago, DHS was THE SPOT to go on NYE when you wanted to have a NYE experience, but didn't wanna deal with the crowds at Epcot or AK. We'd go to MK on 12/30, then head to DHS NYE after a nice dinner. The park was so wide open with people gravitating toward Streets of America for the Osborne Lights...and after I turned 21 we grabbed some champagne near Tune-In. My sister and I would kick off the new year by going on RnR, as the park would stay open until 2am with EMH. During construction, it became less desirable and only stayed open until 1am. I predict they'll return to the old model with higher-than-usual expected crowds. They also do the Star Wars fireworks after midnight which is pretty cool.
Epcot usually closes after 12am, MK stays open until 12 or 1.