First time posting on this site...
As a huge baseball fan, the Colorado Rockies' recent renovations of Coors Field come to mind as a benchmark. Like Progressive Field, Coors Field had a third deck in right field, and they replaced most of the seats with a "rooftop party deck," which can be seen in the photo attached below and on photo galleries on the Rockies website.
I wouldn't be surprised if something similar is in the works for Progressive Field. IMO, the 500 level in right field there are some of the worst seats in any park in baseball, as they are about 500 feet from home plate and 150 feet up, so they will not be missed. Plus, I attended the Indians-Royals game on July 4 and noticed that despite the game officially being a sellout, the right field upper deck tickets were not sold and were draped with an American flag.