if maybe an Arkham expansion could be made like that. Maybe a sort of specific adventure for different AOs where the players would encounter a few scenario specific entries for each location. Possibly even an additional final battle scenario. A book wouldn't take up that much more room on the table and FFG already publishes books.

That's a pretty interesting concept actually. Sort of a variation on the small box expansion and the league scenarios.

Some specific cards to support the "campaign" that come with the small box expansion as well as a booklet with scenario details for locations as you mentioned. Then like the league you'd get scenario setups with specific rules, a specific AO, and required investigators/allies along with environment conditions.

It'd be neat if there was something like Runebound's map overlays maybe to change perhaps an expansion locale without requiring the printing of a fully mounted new board. Perhaps even just location "counters" made of cardboard to cover up the existing locations on an expansion board.

I like the overlay idea. AH is such a great system the variations can be endless.