Cost to replace "wall of glass" with sliding doors?
I called a well-regarded Chicago-area window company and gave them the specifics.  From our discussion, it sounds like replacing the hardware might be a possibility depending upon the manufacturer.  

Otherwise, the wall from the top two pictures should be about $8,000 to replace just the lower sliding glass doors and the stationary panels to the left and right.  I didn't get the impression that replacing the upper panels would be terribly costly in comparison if we decided to do those.  It sounds like the fact that there's a structural beam in place (above the doors) helps keep cost down.