There are few examples of attractions which get everything absolutely perfect.
ToT definitely fits this:
Setting, Music, Location, Presence, Duration, Story, Costumes, Throughput, Lighting, Layout, Special effects, level of thrill/excitement are all perfect with this attraction.
There is little about the attraction which could be improved in my view, to retheme it would be a monumentally stupid decision which if true will be hard to beat. I am beyond surprised this is even being considered and it honestly makes me question if the management have any clue what makes the Disney Parks so special in the first place. It really would be a new level of stupidity.