If the Momusu thing gets passed on to the ex-HPK, she should be getting a PB just before she turns 18.
I still think that eventually there will be a flood of Berryz/C-ute PBs for those that don't have one yet, just like they had one for the less popular MM girls a few years ago, before Koharu joined. They'd have to do one group at a time tho, because otherwise it would be like 8 PBs.