Against a peer adversary, the A-10 stopped being a Day-1 weapon around the time that it was rolling off of the assembly line. We were simply going to accept higher attrition in the Fulda Gap as part of the plan. By the 90's, the Hawg wasn't even a Week-1 weapon. Going into 2020, the Hawg simply won't be in the fight until ground troops cross the line. But there's the rub--we don't roll ground troops under contested airspace. So yes, the A-10 will sit in the chocks until the air is permissible--and it's going to continue to need cover while it does it's job.
But the capabilities simply do not translate to those platforms which are being counted on to bring down the air threat, and provide cover moving forward. The F-35 simply won't do under the weather, low vis, escort, rescort, knife-fight close proximity...and the list goes on.
To be blunt, the A-10 and it's core TTPs just aren't that far removed from an A-1D over VN. But then again, linear battlefield infantry tactics (at least looking down from the air) haven't either. Leaders have become accustomed to pred feeds and the whispers of the military industrial complex saying "but with this new technology just around the corner, EVERYTHING will be different". My bet is that even in a German Formula 1 team garage, amongst the computers and precision calipers and multimeters, there's still a claw hammer in a drawer somewhere.