Still waiting for the Haunted Mansion redo.
Agree too with a remake of 20,000 Leagues. Could start a franchise around Jules Verne works along with it. Could have Journey to the Center of the Earth, Mysterious Island, and Around the World in 80 Days. Many of these would be stories Disney has adapted before but could make them all connected somehow too while standing on their own to flesh the word out more. Could make a great family adventure franchise.
Though honestly for a connected adventure series of films/cinematic universe I'd really like them to take their SEA organization from the parks and make a film universe around it. The new Jungle Cruise could be the first in it.
Disney has been kicking around a 20,000 Leagues prequel called Captain Nemo for a while now. It would not be a reboot. It's been stuck in neutral for a while though so I don't know if anything will ever come of it. If it did show up, then it could almost certainly lead to a franchise.