I would love to see FFG produce a Runebound campaign game, like they did with Descent.

Such a campaign expansion kit would have no boards of its own, just cards, maybe special counters or markers, and rules for linking whatever expansions and boards a player has. It would not use the adventures that come with the expansions but it would use their boards and, where appropriate, their markers. It would need to have special item cards and adventure cards that link the expansions and allow for the scaling of difficulty and rewards and provide for on-going development in challenges as the characters develop and become stronger (and get better loot, artifacts and weapons). Thus as you move through the adventure/expansions, the monsters get progressively more difficult but the loot and weapons get stronger and better, too, just as your character develops and improves.

There would be a meta-adventure that spans the different environments, taking the adventurers to islands, across deserts and frozen wastes, and to who knows where else to solve some vast threat to the world. And this grand adventure could be scaled to the player. If he/she owns just two expansions, then there's an adventure for that; if three expansions, an adventure for that, and if all four, well, then you play the grand adventure. In effect, each combination of expansions with the base game would have a campaign adventure, or maybe more than one. If they are good and exciting, it would certainly encourage people to buy the expansions they didn't have.