There is no shortage of ideas for additions that Disney could make, especially in light of Potter's success at Universal.
In my opinion, a logical move to make in response to the growing competition from across town would be a major expansion of Pixar Place. Though no one Pixar movie is anywhere near as popular as the Potter series, the combined library is as strong. After adjustments for inflation, I believe the films from the Pixar studios have generated more than Potter at the box office. Add the revenue from merchandising, and these films truly are, as a previous poster mentioned, some of the most valuable entertainment-related assets available.
With this in mind, Disney could easily combine these products, expand upon an underutilized, existing land and create a formidable package. And, it could possibly be done for less than an Avatar addition.
Most of the ideas for changes and additions to this land and the surrounding areas have been mentioned before. But, just thought I would throw out my preferences...
-Convert "Honey I Shrunk the Kids" movie set playground to "Bug's Life" playground.
-Enclose Studios Catering Co. and turn it into the Pizza Planet complete with the now famous delivery truck.
-Remove BLT
-Replace Cast Member Costume Center with Monsters Coaster and move the Laugh Floor into the same building/pavilion.
-Add an Up attraction: either a dark ride along the lines of Peter Pan or something as simple as a well-themed version of the old skyway (or, potentially, a combination of these).
-Add an Incredibles ride. What I have long been picturing for an attraction now lacks much innovative appeal following the introduction of the Seven Dwarfs Mine Ride. However, my idea was for an indoor/outdoor family-friendly coaster. The queue and indoor section would replace the BLT Pre-Show/queue. The outdoor track would run the length of the NY street. Cars would sway and "skate" along on a Frozone-created ice track atop the building facades. Throw in Edna Mode, Jack-Jack and the entire family, and there is potential for many complementing story lines.
-Add a Cars version of Autotopia where the Operation Support building and Catastrophe Canyon are now located. If possible, incorporate part of the canyon. Extend the desert theme by building out the rock wall facades throughout the attraction.
Then, relaunch the land (and DHS) and market, market, market this package of attractions as all new.
Such a decision would allow for a transition of the current Pizza Planet to something with a Muppets theme. Plus, open up the current Tomorrowland Speedway and Monsters, Inc. Laugh Floor locations for new attractions. TDO may not be as keen on this latter portion, but I suspect many guests would welcome the changes.
Just some amateur thoughts.