The original 50th plan actually was to replacing HEA with park-focused nighttime spectacular, like RDCT, Celebrate! TDL, and Epcot Forever was, which contains past, present, and future attractions/shows at WDW theme parks and minimal IP appearance. A nighttime parade also being planned then.Just my opinion but I think we wouldn’t been way better off with just a 50th tag to HEA. The MS projections could have been added to HEA and likely will anyway if/when HEA returns. It is what it is. Can’t help but think the original plan was to keep HEA with a 50th tag then have a light parade, but then they axed a light parade and went with a HEA replacement.
We can't imagine what happens if the original plan goes ahead assume there was no pandemic then. We still have the original song "You Are the Magic" but instead of contemporary Disney animated films and villains like Onward, Frozen II, etc, the pre-pandemic plan of firework show will showcasing The Haunted Mansion, Country Bears, POTC (actually both are perfectly fit in villains section of DE), IASW, MSEP, Animal Kingdom rides, electrical water pageant, etc. where many out-of-state and international visitors don't know nostalgia why the ride is stil exist.
NOTE: It is not purposed, is planned (grammar mistake)