Heck, I can come up with an idea for one right now.
For instance, replace the gun with a submunition dispenser. being able to drop multiple precision guided munitions (PGM) might be a good replacement for the gun. You could carry a lot of 25 lb. bomblets for the weight of the gun and ammo.
I think you have a good idea but not for the A-10. Other platforms already have your idea.
Check out Cluster Bombs dropped from a B-52 or other bomber.