I recall reading somewhere (possibly a version of a DAA plan) that once T1/Pier E opens, that Pier B will be closed. There appears to be structural issues with the area that would require extensive works.
The plan, drawn up when the economy was growing, was to demolish the current B gates and build a straight out pier in its place, pretty much parallel to the new pier. Once that was done, the same fate would befall the end of Pier A.
But with Ireland now returning to a more familiar economic pattern that seems unlikely.
JAS