IronWolf
blank
Since later adventures in the path aren't necessarily finished by the time the first adventure comes out, and because it takes time to sculpt and produce a line of minis, there will naturally be a pretty lengthy gap of time between the release of an adventure path and the release of its accompanying minis set.
Well Paizo knows a good chunk of time what the next AP will be so they do have a bit of a head start. Though they may not know to the exact detail what the critters or NPCs would look like quite as early.
I think people with interest in minis would pick up AP sets as well, just because they are bound to include critters or NPC types they could use in their games even if they weren't playing the AP.
For example, I have seen some people say they would like to see undead packs. A mini set for something like Carrion Crown could likely fill this need as well - even if you weren't playing Carrion Crown.