I’m more inclined to think this new version will largely hit the same beats of the original while adding in new properties like Encanto or Turning Red. That’s the thing about these type of clip shows, they have to keep staying fresh. Watching World of Color for the first time earlier this year, it was jarring to see that none of the movies within the past 10 years were included. Hence why I’m not surprised that show’s getting an update as well.
The big question here is whether or not Main Street will be getting new projections as well.
World of Color has had a number of updates with numerous new characters over the years. WoC: Celebrate! for example was a 60th anniversary show that was pretty much 100% new and only WoC in name only, but it ending up being a bit of a flop. That's my only concern. The only reason the keep going back to the original WoC that's out of date is because it's the best received version by far.
I'm expecting pretty much exactly what you said: updated sequences with not only newer characters, but adding in 100th anniversary segments. The song can only carry the show so far, though.
There's still plenty of ways to mess it up if they screw up the pacing, so i'm going to remain a tad skeptical (although I really want MK to have a great nighttime show again) until I actually see it in person probably in April i'd guess. The 50th anniversary ends on March 31st, 2023, so theoretically, the new version of HEA could debut on April 1.