This might not be a popular opinion in general, but I wanted to toss this thought out while it was fresh in my mind -
I've run a number of Pathfinder APs over the years and the one thing they all have in common - my groups and I never finish them. With gaming groups that only get together weekly (at most!) for 3-4 hour sessions, the campaigns go on for YEARS of real time. The closest I got was the Rise of the Runelords, which I ran for 6 years and then the group fell apart due to you, know... people moving on with their lives. haha.
I, for one, am a big fan of a 3 part, complete story arc that ties everything up and together over 10 levels of experience. I know there are one-off modules, too, but even though a "mega-dungeon" isn't really my style, it opened my eyes to the possibilities. 
I'd love to see more APs with that 3 part concept in the future.
Thanks for all the great content!