So I read some of this thread last night and it really got me thinking about Epcot. I've come to conclusion that yes, Future World is a big mess. It has lost the spirit upon which it was built and literally every attraction in Future World save maybe one or two would need major work to become what it once was.
Ultimately Future World was founded on the idea of intellectually exciting rides. Over time they switched their focus from intellectually exciting to physically exciting, but they failed on that front. At the end of the day Mission Space and Test Track don't hold up to what modern thrill rides offer in other parks. So now it's neither intellectually or physically exciting.
EPCOT was Disney trying to make good on Walts dream of the Experimental Prototype Community Of Tomorrow. Future World was going to showcase the future we could hopefully look forward to while exploring all facets of our world. Arguably that's what it was when it opened in the 80s. You had really engaging and thought provoking rides like Horizons and Spaceship Earth. Sure they weren't exciting the way a roller coaster is, but that was never the point.
I think Future World could be saved, but it would mean drastic changes, such as redoing rides like Test Track and Mission space completely, and refocusing on what made Epcot exciting to begin with, a vision of our possible future.
Just a short example: Mission Space skips over all of the important and exciting aspects of going to Mars, and focuses on just the two that could be easily recreated with a jet ride. The take off and landing? Really? I want to see what life in Space would be like. I want to see what could happen to humanity when it lives on another planet. I want to see the technology we'll use to overcome the problems that arise in sending man across space. I don't care about the G forces of a takeoff and a shaky landing on an unrealistically placed runway at the edge of the cliff.
Anyway I could go in depth over each attraction, but that would probably break the character limit I'm sure. In any case, as much as I love WDW, I'm sad to think about how much better Future World could be if Disney focused on it's core premise.