Here's Tom Bricker's comment on that:
"However, Monstropolis replacing Animation Courtyard would’ve been the costlier and more time-consuming project. Since this is one of the
D23 announcements intended to have a faster turnaround time (obviously everything is subject to change and this is just rumor, but my understanding is that the Monsters, Inc. Doors Coaster is what’s in the pipeline to follow Tropical Americas), they want it done quickly. Well, “quickly” by Disney standards. I’m sure someone else could build a ~90 second coaster in under 3 years.
Most significantly, it’s also my understanding that another (larger) project is slated for Disney’s Hollywood Studios as part of the 10-year plan, and that’s better suited for Animation Courtyard. The general thinking here is that this plot of land has the potential to be significantly larger and accommodate a much bigger and more ambitious project.
If Animation Courtyard were to end up being used for Monstropolis–a smaller project in the grand scheme of things–it would handcuff Imagineering since there isn’t space on Grand Avenue or anywhere else in the park for the next project."
For the full article, see here:
https://www.disneytouristblog.com/m...place-muppetvision-disneys-hollywood-studios/