Speed is not really an asset in CAS (other than being able to get on station quickly). Fast movers have a problem acquiring and hitting targets (sans the use of guided precision munitions). Those are expensive, so the military is going to default to dumb bombs most of the time.
The hit against the A-10 in the 80s was in the high threat environment it was vulnerable. That will be true for any CAS aircraft.
The question is will we have a low threat CAS aircraft like the Super Tucano, or a durable (but expensive) medium to high threat CAS aircraft like the A-10 or something of its ilk.
USAF hates the CAS mission, so I think they will grudgingly go the cheap route of the Tucano. But those aircraft will be meat, in any environment with real AAA assets.
In Vietnam, the Sandys (A-1 Skyraiders) who's lotter time and massive ordinance load made them excellent CAS aircraft were pulled due to vulnerability to the NV AAA threat. They where tough, but not tough enough to sustain multiple hits.
The replacement was the A-7, the SLUF had reasonable speed (to avoid AAA), tubrofan engine allowed useful lotter time, and large ordinance load. But it still wasn't tough enough to take the hits (thus the A-10 was conceived).
They really need to make the next generation of the A-10, taking all the advantages of the A-10 (and lessons learned) and applying new technology (semi-stealth, night strike capability), and it will not be cheap.
But in any form, it will not be cool and sexy, a requirement for the USAF. So either they punt on the CAS mission, allow the Army to fly fixed wing strike aircraft (maybe declare a restriction on subsonic aircraft to make them happy) or they will have to suck it up and go forward.
But the flying wonder that is the A-10 is getting long in the tooth, the airframes have an expected life, even with wing replacements they will time out.