Originally Posted by Troacctid
I think NPC classes want to still be around for gameplay reasons.
I was just about to post this same sentiment. Probably no reason why anything under Tier 4 couldn’t make an appearance. The expert would see heavy use for the artisans who contribute to the city-state temple economies.

Also, I don’t think it’s been mentioned yet, but are there any restrictions on prestige classes? Presumably anything relying on higher-tier base classes would be absent, so no arcane hierophants, but what about other PrCs?

I think mystic theurge with ranger/spellthief is possible, if not exactly ideal, but it could make for an interesting NPC if the PrC is allowed.