Here's my fantasy product, which would solve the issue of a follow-up "Beginner Box 2" type product and also be highly useful to any Pathfinder GM.
How about a Sandpoint box set?
It would mirror the BB in components, having a flip-mat with the Rusty Dragon on one side. A 64-page book detailing Sandpoint and surrounding area, NPCs and locations etc. The larger 96-page book would be a campaign of several connected adventures.
Pawns for all of the important NPCs of the town plus unique pawns to go along with the adventures book. In place of the dice + pregen PC folios a big poster map.