How much does one aircraft cost and how many drones could you buy for that much money?
Imagine sending a few thousand drones into enemy territory to spread out, lurk and creep around. Photo electric cells so they can stay charged, with either inbuilt programming so they can't easily be jammed, or waiting for a Go signal which they'll get once a target is identified - perhaps by another drone
Then if you did a mass attack from all directions, the enemy can fight off one or two, maybe even ten or twenty, but at some point there are just too many and some get through. Granted they don't carry much destructive power, but then again, maybe they don't need to if they can find the ammunition dump, or the fuel dump, or the officer, or the barracks at meal time, or the machinery room , or the parked aircraft ... and they can be super accurate
Think about some of the engagements in WWII that would have been different if we'd been dropping drones instead of unguided bombs. Ploesti for instance: once you got one or two oil tanks alight the fire would spread and the mission would be accomplished
I'm not saying there'll be no need for aircraft in the future, I'm saying there's a change underway that's as big as the introduction of aircraft a hundred plus years ago