Eight months after you posted that question, and you get your wish. The Miceage Update this week explains the focus for Marvel will now be the northern end of Hollywood Land instead of the empty parking lot behind Tower of Terror.
http://micechat.com/132030-disneyland-rumor-update-one-disney/
And then
@sponono88 was kind enough to show us the map that another website, Mouseinfo, made based on the big Miceage Update this week.
Marvel Land expansion for DCA is now slated to go into the orange areas shown above, once the new bus loading zones and skybridge over Harbor Blvd. are completed as shown in the purple "Parking Phase 1" and blue and pink walkway and guest access zones above.
It's a really smart way to use that space I think! And opens up a lot of possibilities.