This entire issue harkens back to something that a former CSAF, Johnny Jumper, foot-stomped endlessly during his tenure a decade ago: effects, not platforms.
His point was that we need to focus on producing the effects needed for "customers" (ergo, whomever the USAF is serving, and whatever end-effect they need) rather than navel-gazing about which particular weapon systems are used to provide the effects. The objective is to have a varied tool-chest (e.g. different weapon types, different delivery systems, different delivery methods) that allows the entire spectrum of kinetic effects that would be realistically needed in a rapid, agile, and efficient manner.
Focusing on a particular weapon system is completely missing the point. Specific systems are chained to the time/technology in which they're built, their cost to operate and maintain, etc., but weapon effects are the same today as they've been since the invention of use of kinetic force to damage or destroy another object or living being.
In terms of effects, this...
...is not so different than this...
...and not much different than this....
...or even this...
These are all methods over time of providing a kinetic force to damage or destroy an object or kill/injure people. Although the mechanism of delivery differs, the effects only vary in magnitude. The delivery vehicles and methods have certainly changed with technology, but the effects remain the same.
So whenever folks get overly animated about a particular weapon type, or a particular aircraft, or you-name-it, they are really focusing on the wrong things. Yes, certain types of aircraft deliver ordnance more effectively than others, and certain types of ordnance provide certain types of weapons effects better than others -- there's no question about that. Those differences, however, are fleeting; as we've discussed many times here, people proclaimed the end-of-the-world over plenty of other weapon systems being retired that "can't possibly be replaced by" whatever system actually replaced them. Guess what: the military still somehow gets the job done, even with those "irreplaceable" weapons systems long since gone out of service.
When the retirement of a weapon or system leaves a gap in capability, then that is certainly a problem. The one I hear most often is that, with the retirement of the Hog, the capability of the GAU-8 will be lost.
Unfortunately, this represents a massive misunderstanding of weapon effects, EVEN by the Army dudes who often foot-stomp the loudest when protesting the retirement of the Hog. A gun provides an important tool during CAS: low collateral damage effects, or CDE, and low probability of incapacitation, or PI. CDE is the measure of damaging or destroying other things you
don't want to destroy that are located close to what you
do want to destroy (like a civilian house that's located next to a military barracks, for example). PI is the probability that the effects of the ordnance delivered will harm/incapacitate friendly troops located close to where the bombs hit. Different types of bombs and bullets have quantifiable numbers in terms of CDE and PI, and those numbers are used in helping determine which weapons will be used in which situations. Bombs generally have big CDE and PI distances; bullets tend to have smaller distances.
This means when troops are fighting up-close-and-personal with bad guys, and need to "call in the thunder" from above, based on weapons fielded over the last decade or two, bullets can be used at times when rules of engagement (and other restrictions) won't allow bombs to be used. Given the types of combat over in Afghanistan and Iraq, that has meant that strafing became a often-used tactic in CAS because of the low PI and CDE. There are essentially only three types of guns being used by allied nations over that time; the 20mm (in the Viper, Eagle, etc), the 25mm (in the Harrier), and the 30mm in the A-10. Given the relative sizes of the actual projectiles shot, of course the 30mm is going to provide the most damage of the three, and this is what leads so many ground pounders to love the Hog so much.
What they miss in the process, though, is that there are plenty of other weapons out there that have PI and CDE numbers just as low as the 30mm, and also have similar precision and weapons effects. Unfortunately, the delivery systems for those other weapons -- UAVs, and Pilatuses, and really tiny bombs coming off Raptors and Strike Eagles and soon-to-be Lightnings -- just aren't as sexy and intimidating as the Hog and the gun. It isn't as psychologically satisfying to have that same weapons effect come from a turboprop buzzing around, or a big remote-coltrolled airplane, or a dinky little bomb dropped miles away or up high by a fighter. Again, the weapon effect is the same, and those other weapons and other platforms can be just as effective at delivering them as the "traditional" aircraft used to create those weapon effects. The retirement of the Hog doesn't leave a gap in capability -- it leaves a gap of method of attaining that capability, which is a loss, granted, but one that is easily compensated for. As has been said many times, there is no one aircraft, no one weapon, that is so singularly capable of anything that it is irreplaceable.
So, long story short: every time someone focuses on a particular platform or a particular weapon, they are totally and completely missing the point.