User blog comment:Salubri/Aizen, Yamamoto and Wonderweiss/@comment-1454424-20100227020425

Once again, the Arrancar Arc (that's what Kubo calls it) that started in volume 21 will be coming to an end mid this year. So June/July, the Arrancar Arc/Saga/whatever you want to call it, will be over. After that there will be short arc and then a long arc. I imagine the short arc will have about as much relationship to the Arrancar Arc that the Soul Society Arc (volume 1 - 20) had on the Arrancar Arc. I.e. somethings will be resolved at the end of the Arrancar Arc, other things will carry forward into the Short Arc and resolved there.

From what I gather, the main purpose of the short arc is to set things up for the long arc - which may or may not be the last arc of Bleach as a whole. Kubo doesn't work of a plan so it is pretty unusual for him to say definitively that there are two arcs coming, given that's pretty much a five year plan. But the long and short of it is, that after this arc the focus will not be on Arrancars.