All they would really have to do is move the few hangars that are on the lower southwest corner of the "airport" along terminal dive and add a fourth terminal similar and mirror image to terminal 1. They could move the hangars over by wetmore and the railroad tracks or just rearrange them along the eastern side of Jones Maltsberger. As an example of a landlocked airport; I have a picture of a land and water locked airport.
Here
IT is. It would be too big to post on here.
Reagan is busier than Austin and SA combined; but it has most of its hangars neatly arranged (on the left side of the picture) along GW Parkway, not scattered around like SAT does.
Here it is on a map.
Reagan does have two luxuries that SAT or AUS don't;
being 20 miles from Dulles and 25 miles from BWI (both larger and busier than Reagan)
and having the Metro line run to it (which the other two don't have.)
Got info from
wiki.