I'm starting to believe that marvel will be tucked in the South east corner of DCA. With Bugs Land as one portal off the Main path and GotG:MB as the portal coming off the Hollywoodland area. Leaving the Backlot, Hollywood Blvd and Tram Drop area as expansion. I think the delays in the 2nd parking deck are forcing them to change plans with where the marvel area actually gets built because that tram area wont be ready for expansion for a while. Its obvious they want marvel to be the count punch to Star Wars to #1-soak up overflow SWL and DL crowds. #2 - make DCA even more attractive/relevant to day visitors and tourists. #3 - draw Marvel only fans into a Disney park to experience that IP. Its an expensive period of build out for the resort. However it will almost certainly pay off in the long run.
Plus the Hollywood area would still be a feasible area for expansion inside DCA (like TL inside DL) giving the resort plenty of room to add new attractions through the 2020's. .