First reported by StitchKingdom.com, Disney will be taking advantage of the vacant plot on the Mexico side of the Norway Pavilion. According to documents filed with the South Florida Water Management District Office a new building will be constructed on the vacant plot of land. The project is described as the "Frozen Meet and Greet Building" and is approximately 13,000 square feet of space. The below image (Copyright Disney) is from the documents filed and includes the new building that will be constructed between the existing Mexico and Norway Pavilions (click for larger image).
The building is expected to house a Meet and Greet as well as a woman's restroom. This is in addition to the makeover currently underway converting the extinct Maelstrom attraction into a Frozen themed ride.
The history of the Frozen additions to Norway rumor can be found here.
A look at the layout of the former Norway Pavilion courtesy of the enfilm Flickr account can be found here (click for larger image):
The new building would be above the building featured in the blueprints above, between Mexico and Norway.