They cook up all sorts of BS excuses about the costs of special support equipment for A-10 (already paid for) while blissfully ignoring the massive waste blown away on JSF and F=22.
https://en.wikipedia.org/wiki/Textron_AirLand_Scorpion
Strait-winged, turbofan, six wing hardpoints and an internal bay, extended loiter time, only $20mil+$3k/hour operating costs ... this thing has serious potential.
The A-10 can't be replaced by effectively a trainer with a light ground attack option.
The A-10 is a flying tank, it's main gun is very useful for CAS and it can carry a lot of armaments and more importantly take a lot of punishment.
The A-10 is simply not sexy, the air force doesn't want it, it might not even want to provide CAS roles in general.
The USAF offered the US army to take the A-10 fleet in house the Army doesn't want it since logistically it can't really support fixed wing aircraft at this point, maybe the marines would take it in.
The A-10 isn't expensive, it's probably the most cost efficient aircraft the US has produced since WW2, it's simply not a sexy Gen 5 FBW doodad.
But is too expensive to ever risk danger-close. Whereas A-10's have had mortars fired over them in certain circumstances...
The A-10 was designed to take a beating, it has redundancies on top of redundancies, and armored cabin and fuel tanks, you can blow half of it's tail and it will still land (tho an F-15 has landed with 1 wing ;)).
Light attack/trainers are OK but they aren't in the same league.
The scoprion is interesting, once you get past the new look. It's got roughly the same capacity, size and costs of the A-10. But it's a little faster, flies higher, and of course lacks the legendary 30mm. The second seat (either flown or removed for space) adds lots of EW potential that would make it more likely to not be shot down than the A-10. And there might be room for a fancy big gun in that internal bay. I;m most impressed by it's 5-hour loiter/CAS time. Like I said, the concept has potential.
Radar profile is a minor issue. Normally, the A-10 would be facing unguided and perhaps IR-guided threats. The A-10 has flares and chaff.
I don't think modern radar-guided AAA is much of an issue given the use case. The radar gets taken out, either by the A-10 itself or by something high and stealthy or even by a cruise missile. The larger systems are not easy to move and hide. For the smaller systems, the A-10 can withstand 50mm shells hitting the cockpit armor.
No. Wherever you read that is dead wrong. 0.50 caliber glancing rounds yes, the sort of thing from a machine gun. And it is meant to survive nearby air bursts from 37mm AA shells, their shrapnel, but not direct hits. A hit from a 50mm exploding shell would rip the plane into pieces no matter where it impacted.
Minor correction, from Wikipedia, with references: The armor has been tested to withstand strikes from 23 mm cannon fire and some strikes from 57 mm rounds.
References:
Donald and March 2004, p. 18
Jenkins 1998, pp. 47, 49
Note "strikes", not shrapnel. The armor thickness varies. From some angles, the cockpit can take a 57mm shell. From other angles, it's only good for 23mm.
http://warthognews.blogspot.com/2011/07/from-archives-oif-st...
http://i155.photobucket.com/albums/s314/Lethal_014/EMLandv1a...
Also modern MANPADs have sustained supersonic speed which is why they are only good for 4-5KM, but within that they'll splash you at max speed. A SA-18 traveling at 800M/S+ has only a range of 5000M so there isn't any "coasting" this isn't a movie they fly for 5-6 seconds and either hit something or drop like a rock.