"In my view of the issue, the fundamental problem with the entire role of the A-10 is that it forces you to get very close to the ground and approach enemy forces directly."
Explicitly no, that is the strength of the A10. Eyes on target rather than sensors on target allows discrimination and judgement to be used. Your argument in favour of high or medium altitude CAS falls apart on a simple question of airmanship. Can you positively identify the target?
Zoom with sensors of whatever nature or resolution does not give you situational awareness, nor does a ground operator using the delivery platform as a remtoe contol. Even forgetting bandwidth concerns this is a political expedient rather than a combat solution. You are also conflating two issues, the use of standoff weapons such as the Maverick and the use of guns. Neither has a simple envelope or ROE but it is the guns which provide a unique capability due to the A10's ability to withstand AAA fire. Dissimilar aircraft cannot perform the same role as their low speed handling does not allow them to remain eyes on whilst manouvreing.
The A10 is frankly, a sub optimal platform. Whilst relatively cheap in US terms it simply is not fast enough, or more explicitly does not provide the acceleration or dash speed necessary or it's role. Standard practise was to run engines at max with boards out to rectify this, though this knackered the airframes. It is not explicitly a CAS aircraft but a tank buster designed for Western Europe . Very few missions in the modern timeframe would envisage confronting armoured columns close to the FEBA , though interestingly this is one of the key design parameters of the F-35.
A-10 losses in combat were practically insignificant even compared to peacetime rates. It proved itself, if anything, to be almost impervious to AAA and manpads in a third world scenario. Loss rates of over 5% are historically unsustainable, less than a tenth of 1% a pointless discussion.
The airframes deficiencies are a lack of dash speed and acceleration, the big gun almost irrelevant against anything other than serious armour. Frankly a minigun armed A37 Tweet could perform 99% of the niche missions more effectively and at less cost in maintenance and basing. F-35, EOTS, SDB and any other medium altitude solution however is in no way a replacement for the A-10 with it's emphasis on pilot skill rather than technology. Medium altitude may sound enticing to rid yourself of the ground menace, but try hiring a cessna and climbing to medium altitude to see what the world looks like and you'd soon change your tune if you picture yourself on the ground facing small arms fire at 100yds range.
The A-29 is another avenue to this but one which suffers the same dash and acceleration issues as the A-10. You don't need a super-cruising hi-tech multirole to perform cas but replacing a 360 knt A10 with a 280 knt A29 is not a solution. Design something which can transition at 500knts+, take some damage ( not proofed against 23mm, 50 cal would suffice) , wield a medium calibre gun with a high rate of fire and double as a bomb truck with a low Ir signature and you have a solution of sorts.
Frankly carefree handling, visibility, low stall speed, MTBF and endurance are far more important than any issues you have rasied. You'd be better off asking an infantryman what he wants than gesticulating in the dark about future technology which is more likely to get them killed than help them.