I think fifth generation fighters would force the VKS to operate rather far from the front even without a significant suppression effort. If F-35s can be lurking a few dozen miles back from the FEBA, or worse F-22s, it seems to me they can reach out and engage any Russian fighter as soon as it makes itself a threat rather easily. They may have to immediately maneuver and not be able to guide their missiles all the way to target, but it seems like they would be in a position to drive opposition away with little risk to themselves.
(1)can they?
I am kinda doubtful that anything modern, big and manned will lurk(high) nearby on more or less same conditions(lo/no regardless), especially if it isn't even broadband 360 VLO. Attrition will kick in fast. Even Ukrainian AD network(Fulda wargame collection) has proven itself formidable - Soviet legacy battlefield SAMs in cover-heavy ETO environment are just a menace.
Russian AD threat is generations ahead in quality, in numbers, and it is backed by relevant airforce and strike capability.
(2)For AWACS(loitering aircraft by mission) engagement isn't "operation"(meaning continuous presense), it's darting in into launch position. Midcourse updates can be provided by others. Russian modern aircraft selection is such that there's plethora of options. Near future options(if they're even future yet?) provide more still.
(3)AWACS are rewarding targets. Given relative weakness of E7, pushing them out of effective envelope doesn't appear too difficult to outside observer.
Suppression efforts need not handle the entirety of Russian AD to make a little more wiggle room for support aircraft to operate in.
As Ukraine amply shown, they not just need suppresion, the need is full DEAD, to full threat depth. You can suppress enough semi-stationary AD networks for tactical aircraft(that can break ambushes). It doesn't apply to 707 or 737 the same way it doesn't apply to Il-76 or Il-18.
Otherwise, SAMs just emerge from cover, already hot and primed for launch. "Even" Ukrainian vanilla Buks proven themselves deadly in this role. Much(most) Russian ones aren't old; threat from such pop-ups can go extremely deep into blue rear.
If something like wedgetail is engaged at altitude, it will die.
As for aging NATO aircraft, the legacy aircraft are older but well updated, with USAF F-16s getting AESA. And there is no shortage of F-35s, even if they do not yet outnumber the VKS on the continent yet. The USAF has about 500 fifth gen aircraft by itself; any Russian effort would have to be complimentary to a Sino-American war for the disparity of air arms to not be overwhelming.
Yes, that very well updated F-16s which we see in Ukraine. Better AESA(especially one that doesn't even provide more range for fighter fire control) doesn't change anything substantial here in my opinion - it's a mission where defensive aircraft can launch by external queing. The problem is getting weapon in time into range, reliably, every attempt, and doing it in such manner that outweights attractiveness of a very juicy expensive target full of operators(who, as practice sadly shows, won't even get chances to out).
F-35 are, for all their modernity, are arguably the single worst modern interceptor aircraft out there. More so because there is no even LO fuel tanks for them.
Yet it's interceptor qualities that are needed for the mission - loiter qualities on one hand, speed of reaction and reach on another.
Especially since attacker holds initiative by default(i.e. can easily have local numbers and chose opportune moments), and opfor(VKS; PVO SV) contains arguably single most annoying VL BVR setup out there - other than Su-30 family maybe, everything else is pain in its own personal way.
Yes, chinese aircraft are far more numerous and their electronics are arguably better - but they're all far more
conventional, direct threats.
