There has been very little air-to-air combat in a long time. The majority of combat has been developed super powers against 2nd or 3rd world states, or against entities that aren't even states at all.
The only fighter air power requirement is a few hours of work to make sure that there is total airspace superiority, and then every other attack/recon aircraft in the super-power's arsenal loiters over its targets unopposed.
The software & silicon revolution is going to throw a wrench in all of this very soon.
Suppose you are ISIS. You cannot build all the infrastructure to have an airbase with fighter jets and trained humans to operate and maintain them, etc, and even if you could, the super powers would just stroll by and put a crater in your runway.
So what you need is an assymetric response to air power.
In the Soviet/Afghan war, the US funneled stinger missiles and other man-launched AA and AT weapons to the jihadists, and they were able to cripple the Soviet war machine.
The folks in the middle east are already plenty good at making IEDs - they have the "warhead" part figured out.
What's to stop them from putting ArduoPlane brains inside of RC powered jets and putting IEDs on them, and then using optical seekers (e.g. no active emissions, so the big jets never know its coming), and then shooting down low flying aircraft of all types and configurations?
The per-unit cost for something like this would be under $10k per copy. The impact of shooting down just one super-powers aircraft would be tremendous. It would cause an operational re-think and might even change the balance of air-power in the theater.
The Superpowers are going to need to stop playing the manned-aircraft one-ups-man-ship game, and embrace low cost swarms.
For each ISIS fighter that launches a home-made SAM, the super-power will need to respond with a swarm of airbone hunter/killer drones... already nearby, on station.
I think battles between various super-powers competing 5th gen manned fighters are unlikely and will hopefully never happen. I desperately want to avoid a shooting war with Russia or China...