There's a DAA annual report from a couple of years back, can't recall which, that stated the "B pier"/300's need significant remedial work as there is a crack that affects the structural integrity of the structure. The plan was once T2 was live that the pier would be closed, repaired and extended to accommodate more stands. IIRC, an extension was also proposed for what was the A's, now 200's.
IMHO, that's not likely in the short to medium term. My guess is that the new ATC tower is the priority development at the field as it paves the way for 28R, then toss up between additional gates/pier extensions (repairs?) or 28R post 2020.
JAS