I bought Unseen Forces because it actually expands the core game whereas all the other expansions seem to 'replace' it by using the core assets to set up an entirely new/different game.

Are there ANY assets in the other expansions that could be applied to the core game to make it even bigger without replacing all the decks (i.e. new investigators, new abilities, etc.)?

Well, Grave Consequences adds 3 new decks that can be added to the base game. But your right that all the other expansions add specific story arcs which play out independently.

On 1/20/2020 at 7:55 PM, ArcadianDelSol said:

I bought Unseen Forces because it actually expands the core game whereas all the other expansions seem to 'replace' it by using the core assets to set up an entirely new/different game.

Are there ANY assets in the other expansions that could be applied to the core game to make it even bigger without replacing all the decks (i.e. new investigators, new abilities, etc.)?

Investigators, Items, Spells, Allies. That would be pretty close to a definitive list of universal components.