Well The conventional Air power as we know it evolved over the battlefields of WW1 as Scout planes evolved. Pilots from the other side crossing each other and the enemy lines first could only signal each other then someone realized they could try and attack so some Barnstorming pilot dropped a grenade. Eventually some pilot on the other side said "if he can drop a bomb I can shoot him." and then the grenade became larger and the pistol became a machine gun. and the speeds got faster and the loads became larger and after WW1 someone realized that if you can drop a bomb you can drop a soldier and things evolved from there.
Now Even if the Top tier nations get your super tech that is going to leave smaller less well funded nations who will continue with what they have and likely look to use the relic surplus aircraft of the top tier nations.
Also Just because you have your super weapons it does't necessarily mean that all the missions of Air power are filled. Think about Intercepts of Civilian aircraft, Transport of Military forces and Logistics. You are still going to have lots of options. on the conventional side unless you develop Teleportation.
The basics of Airpower would still apply. And although Your deploying some form or super weapon that might have a global reach you have to think about the speed at which small attacks could still happen. I mean Were assuming that stealth is out fine, but what about range and time and size? Think small drones. If you have your super weapon trying to Clear the skies of a theater ranging into the stratosphere. What do you do about Low altitude attacks? Small Drones launched in swarms each weighing dozens of pounds flying at high speed and maneuvering. sure you can try to wipe them out but if they are mixed among the buildings and surface clutter those can still get in close to your troops and make a mess. pop up guerilla warfare.
You know Sol, back in the early 2000's I remember there was a Larry Bond Novel That this is reminding me of.
Lash Up by Larry Bond.
Remember this was from the early millennium and I suspect Bond had written it even earlier So it's a bit dated on tech but the Story was that the PRC deployed a Gerald Bull Super Gun and It was knocking The US out of Space, by destroying Communications and GPS satellites knocking holes in the US ability to react well simultaneously making big pushes Against US Allies in SEA.
The US has to respond So they launch a crash Course of launching sats to fill gaps and building tech, They repurpose the Venture star from Lockheed Martin.
Venture star was supposed to be a single stage to orbit Space plane aimed to replace the shuttle, It was canceled in the last days of the Clinton administration. Anyway they arm the Venturestar with lasers and Rods from god. They goat the PRC, into destroying a few more satellites. They use the sacrifice to triangulate the trajectory of the Asat round and then the point of firing.
This is a important point here about the Relationship between Space and Air power. In both it's all about DeltaV. but in a Atmosphere it's Drag vs Lift. vs in Space where it's Thrust and momentum vs Gravity. Less Top Gun more butterfly effect.
In Lash Up, The PRC figures out what the Us is up to and Threatens to destroy the Craft before it can deploy against them. The Crew of the Venture star renamed "Defender" uses this to there advantage. They leak the launch and plan it for the night so that the PRC can see it, and know it's happening. They then have a false launch using a fighter jet on afterburners and the low light to Trick the PLA gun crews into firing. This is important because of orbital dynamics. For an Intercept of a object in space, you need precise timing of when the object will be in just the right spot for just the right moment to align.
By performing the False Launch stunt the Press and any agents in the crowd would see it and think it was the launch and transmit the time. By transmitting the Time of Launch and calculating the Mass and location vs the known Trajectory The PRC gun crew would have programed the counter launch to intercept for the best launch window. Mean time after a few moments the real launch took place placing the attack in a different orbital window. The fired gun ( in this case by being a Bull super gun) is used up and the Defender in the story launches attacks on the Super gun, knocking it out and make strikes against the PLA from orbit.
By being in orbit It could launch it's strikes thousands of miles away from targets and be well out of conventional interception range.
Overall Though. I really think that in the end as long as earth has a atmosphere and Man has powered flight Air power will be a critical.