If you want edutainment, then the answer is: planetariums (plural, because you'll need more than one dome for the throughput).
And here's the great thing about planetariums: they can be educational and entertaining.
And for those who want what's in Epcot to be different than what you can get elsewhere, and for the Disney brass that wants synergy, the good news is that a planetarium is basically a giant screen. The fan-favorite and commercially viable IPs can show up in the planetarium's show from Miles to Pigs in Space, to Guardians of the Galaxy.
Four domes the size of the one in NYC Museum of Natural History can fit inside the shell of Ellen's Energy. It can be a huge people eater.
Shows can change over time, or different shows be available the same day. Disney can buy off-the-shelf planetarium shows that exist and plus them, or, create their own (which they can then sell to other planetariums after an exclusivity period).
Situated between Planet Earth and Mission: Space, a planetarium would be the perfect thematically.