There isn't really much wasted space. The buildings around Sting Alley are Starbucks, Ben and Jerry's and storage space. Finnegan's takes up an entire block. Louie's takes up an entire block. Almost everything on The Mummy's side of the street is The Mummy. And an arcade. The only thing they could potentially add is a very small walk-thru attraction where the extended queue currently is.
As for SF, you used to have the restaurants on one side and the attractions on the other. The building for Fast & Furious is quite large, so it will continue to take up that entire side of the street.
You can always use Google Maps to get a better idea of how things are laid out. The current satellite image is outdated though. It was taken inbetween demolition and construction of F&F.