I think you have this right. Concord has the potential to create great sets (the Ray Charles ABC Singles box being a good recent example) but. . . why should they in jazz in this day and age of cd devaluation.
My understanding/memery is that the last of them came out under Concord, but had already been in the pipeline from Fantasy. Concord has conceived nothing.
Correct and some completed sets seem to have been abandoned.