Here's my completely ridiculous, grossly expensive, and guaranteed to tick off a good deal of people, but also draw in tons more people idea:
Leave World Showcase as is, except maybe expand (if possible) to add a few more countries and restaurants. That's the easy part. Here comes the meat and potatoes. Be prepared to love or absolutely hate this idea.
Completely revamp the rest of Epcot into a massive extension of the Star Wars expansion at DHS. Redo Spaceship Earth into the Death Star. Turn the interior into a recreation of the hangar bay scene from A New Hope with vehicle props. Maybe have a section of the Millenium Falcon that you could go up into and tour around. Have a large cinematic screen where the hanger bay doors would be that would be able to play a loop of Imperial ships flying around outside to add to the atmosphere. Re-imagine Future World as Mos Eisley or Mos Espa, or a similar port with Star Wars themed shops and at least one big-draw Star Wars themed TS (or signature) restaurant and some CS options, and at least one bar/cantina with various animatronic and costumed aliens inhabiting some of the spots. Change Soarin' from a flight through California to a Snow Speeder flight through Hoth with some flying through the battles with the AT-ATs. Change Nemo to a ride on a bongo through the oceans and core of Naboo. Change Test Track to a speeder bike run through Endor. Add more character meets. Here's the big one: build a train that connects the Mos Espa in Epcot to Mos Eisley in Hollywood Studios. Have the train cars set up like the Harry Potter train at Universal, where each of the cars has enclosed areas that are mocked up like the cockpit of the Millenium Falcon, and the ride between the two parks is a cinematic adventure where you escape the port, outrun the Imperial fleet, jump into hyperspace, and eventually arrive at DHS in the Mos Eisley section of the Star Wars area. During the "flight" over, you're escorted by X-Wings and A-Wings that take out TIE Fighters and clear your departure and arrival points.
It would alienate a certain amount of people, to be sure. It would also drawn in a ton of Star Wars fans and become a mecca to all things Star Wars. The Falcon run between Epcot and DHS would potentially increase park hopper pass sales just for the access to that ride. Sometimes you gotta spend money to print money.
