There isn’t enough customer interest in the B to warrant bringing it to the market, so LM/SAC took the decision to shelve it for now (ever?).
As for the A+ option. Just start with a new build Baseline S-92A and install the A+ kit as a Customer Option during Completions.
I suspect SAC will likely lose millions on each sale, as there is little efficiency or continuity to be had in starting up an idle production line for just a few platforms.