The rumors are obviously sourcing from a couple main themes:
A desire to "finish" and theme DHS, a need to update Epcot, and a desire for Marvel on the east coast.
Look at the rumors... they are all based on finding a theme for the rest of DHS. Sorcerer Mickey in the Theater, Goofy in RnRC... connect them once Star Wars Land opens and you can take out the theater... there's a "classic" Disney original character theme that could be built there. Its workable. The other option, is go Marvel. Big Hero 6 theme of rockn roller coaster, GoTG into the Tower... however, that's already been proven unpopular. So, float it, pull it back...
Which then leaves Epcot... if Marvel won't fit in DHS, maybe it goes in Epcot which needs an update. So now we have the Marvel in Future World discussion...
Point being... it makes sense if you are Blue Skying multiple needs. They are going to be in flux and bounce back and forth until you align on the right plan. Sounds like what is going on here.