I would argue that the mistake that Disney made was not in building yet another Tomorrowland that would become outdated, but in not really sticking to the format they set up for Future World, with moderate investment to update the existing attractions and significant investment to EXPAND the park. Moderate investment to update the finales of Spaceship Earth, Energy, Motion, exhibits in ImageWorks, The Land, The Living Seas, effects and aesthetics in Horizons, working with sponsors to switch out venues in CommuniCore, etc. Major investment should have been spent on ADDING attractions to Future World, instead of replacing them. Journey Into Imagination shouldn't have been touched. Test Track should have been added to World of Motion. Space should have gotten a big Life/Land-style pavilion and not replaced Horizons. But the Eisner regime didn't the same vision as the one the park was built with, and the vision (or lack of one, seemingly) they had didn't end up serving the park well in the long run. But WED built the majority of the park to last with bits and pieces that would need to be updated. Look at Spaceship Earth for the best example, because they've more or less followed the plan with that one.