Modern IADS / SAM-systems (on both sides) are indeed the main reason, which is also the main cause for the Russian AF not having established air-superiority.
But I was talking about just one factor in the whole matter; the F-16AM/BM with APG-66V2 radars (and Mirage 2000-5 with RDY) not being able to match the capabilities of the Su-35 (as was to be expected, and as mentioned (e.g.) in the MWM article and as in the quote by Squirrel from that particular article). I´m sure properly trained Ukrainian pilots would have scored other AA-kills by now besides downing cruise-missiles and drones, if they had received up-to-date Typhoons (with Meteors), or perhaps even brand new F-15EXs (with AIM-120Ds). But that was never going to happen.
Air superiority or air dominance ,whatever .What are these in fact? AS/AD is about one thing only and it is height, altitude, again whatever.So height of the flight in which fighter-interceptors can ensure that AS/AD during as long period of time as it is necessary. ''Higher the fighter-interceptor is ,greater will be its radio horizon''. Also launched AAM's will have max of kinematics and energetic potential. Simple.
Of course, we must count on the ''flying radar stations'' (AWACS) with their 360 degrees surveillance/search of the air space because fighter-interceptors will almost always begin their AS/AD missions in the complete radio-silence. Also ,all radars in the fighters can only search in one given sector simultaneously that is often limited by max 120-140 degrees-azimuth and 120-140 degrees-elevation.Su-57 in that domain is something new because with its eight AESA radars it has capability to search air space sector 270 degrees-azimuth and 120 degrees-elevation ( in the same period of time of course).
Now, ,as far as I know, there is only one operational real fighter interceptor in the world which can fly and patrol for a long period of time in the 'upper stratosphere' ,above the Armstrong's line and it is MiG-31BM. Even Su-35S can't do that,not even F-15C or F-22A or any other NATO fighter at all.So if we take in account constant surveillance missions of A-50U ( about 10km) and constant patrol missions of MiG-31BM ( if would be necessary 20+km ), there will be little or no chance for the Ukrainians even if they get F-22A Raptor 'cause they will be detected/tracked during climbing to medium/high alt. UkrAF fighters can fly higher only above central and western part of Ukraine, that is known but in the vicinity of VKS operations and missions they always fly very low. That is fact and it is mentioned by many UkrAF pilots.Simply, they have no long range AWACS in the sky, have no fighters with long range radars/AAM.Even if they would get all of that ,problem for them will be height and endurance of its fighters vs VKS ones.
Another thing ,if we count on the new stealth Su-57's, their AESA radar capabilities, Product 180 and 810 long range AAM's ,chances will be even more less. From this war and the 'Oper. Sindoor' May '25, we 'learned' that even 9G-capable fighters can be engaged from more than 200km of distance.
For now, VKS fighters like Su-30SM/SM2 and Su-35S patrolling at about 10-12km are enough to ensure complete AS/AD in the war zone. Of course ,MiG-31BM also patrols and I think there is no need for patrols above so called Armstrong limit.
