I agree with much of what you say, but I think you're limiting your imagination in drones' current and imminent capabilities are.
Drones can, and are, replacing fighters and cruise missiles, if not make those ideas of weapons platforms entirely obsolete. Autonomous jets exist already, you may have not heard of missiles composed of thousands of small single-use bombs with onboard auto guidance, which also exist already.
While yes, loitering is a strength, it is far and away not the only thing a robot can be engineered to do.
The bigger idea here is the problems being solved when diplomacy breaks down into violence. You seem to not be aware that modern warfare consists of Shock and Awe. Not like the movies. If there could be a combatant in an office building in the next village, you call in an AC130 and you blow up the building. The idea is that warfare isn't a battle of contrition, but a battle of financial resolution.
So, looking at it from this angle, yes; the natural evolution of warfare will be robot on robot until one side runs out of the ability to make more robots.
Everything else resulting from this has been stated already.
But I think you're just underestimating human engineering and imagination.
Is there any professional reporter that doesn't sell fear these days ?