Marine Infantry. The 30mm is overkill for CAS. We got the same effect by having an F18 come in hot with the afterburners up as with the A10, or doing a 20mm gun run. The beaten zone is huge on those things. If we need to smash a target, a missile as more accurate and artillery covers a large area very effectively. We don't use them because they're good, we use them because we have them.
The A10 does have hangtime, so if we want to replace that CAS ability something like the OV10x or maybe the AT802u, which is a light utility plane with light ground armor and a good CAS loadout. Alternatively, we keep using Reapers, which also have good hangtime. Any of those is as CAS capable as an A10.
The JSF can dodge missiles better than the A10, likely better than the Hornets as well. Everything is electronics and manuverability. Someone will doubtless link the "JSF can't dogfight" so i'll look for the debunking on that one.
If I sound like the cheering section for dumping the A10, it's because there's no option for keeping them. There are no more 1980s missile batteries that we need to fly A10's through to hammer enemy armor columns, and the A10's are reaching the end of their service lifes. As the airframes fail, we have to scrap them. There is no option to keep repairing them, because we would be completely rebuilding the aircraft. If we're making all new aircraft with brand new avionics, airframes, new factories, and new pilot training programs then it's time to take a good hard look at that particular aircraft and as why we aren't replacing it with something that will answer the needs of the next 40 years instead of the last 40.
The greatest fault of the American military has been our tendency to prepare for the last war instead of the next one.