If DC is removed, it seems logical that a family-friendly Forbidden Forest dark ride would replace it, based on the location. The London Studio Tour is adding a Forbidden Forest tour this year, with interactive trees as well as Aragog and Buckbeak, and it's about time Universal does so, as well.
The DC area connects the Hogwarts Express to the Hogwarts castle/frog choir stage area, skirting Hogsmeade. Thus, upon disembarking from the HE, guests would be able to either walk to Hogsmeade or board a thestral-led kuka carriage to Hogwarts. The queue for the carriages would take you past the Shrieking Shack in the distance, which would disguise the show building. As you travel towards Hogwarts in your carriage, Lupin in werewolf form leaps out towards you, driving you from the path. The thestral-led carriages take off into the Forbidden Forest where you witness the swarm of dementors above the edge of the lake and the near-death of Sirius Black. You return to the path just in time to see Sirius ride away on Buckbeak before exiting your carriage just behind the frog choir stage.
In addition to this E-ticket (yes, I said it!) family-friendly ride, the forest would be extended, and a Ford Anglia photo op, similar to Sirius Black's motorcycle in Diagon Alley, would be added. An Aragog, Buckbeak, and/or Thestral Encounter would be added as well. A giant Whomping Willow with an entrance to Shrieking Shack restrooms beneath its roots would be the icing on the cake.
Since the new ride entrance would be moved closer to the HE station, the current DC entrance could be closed and replaced with a real Madam Puddifoots in the next phase.
After this phase, the final HP phase would replace Fear Factor with the Ministry of Magic. As for Fantastic Beasts, there is no telling where Newt will travel next. He might even travel to some land that resembles the Lost Continent in a future movie, or to a location that would be incorporated into the 3rd park.