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.
My idea is that the plane should be able to quickly engage multiple targets with small PGM bomblets; you get it on the right course, program the bomblets (laser designation, GPS, whatever), cut ‘em loose, and hit multiple targets. The plane would only designate for some of its attacks. Ground troops could provide guidance for others.
You can also have different types of bomblets - HE, HEAT, incendiary, thermobaric, etc., for different targets.