What I would like to see would be any of the following:
A full-blown urban campaign set in Taldor.
A return to the Mwangi Expanse to search for remnants of Jtembe's legacy.
An expedition to reclaim a Sky Citadel.
A Wuxia style Tian game.
An AP centered around discovering the truth behind Aroden's demise.
Hollow Mountain.
A large-scale conspiracy game where the Aspis Consortium are the obvious bad guys, and it is evident right from the relative beginning, instead of the usual learn about the plot somewhere around book 3. The mystery would be in figuring out the goal, not the bad guys.
Building a Better Man - the truth behind Hermea.
Sun Temple Colony or explore lost Azlant while dealing with Mordant Spire.
A heist game where what is stolen is far more trouble than it was worth.