You must be very patient if you believe ammunition to be degradable enough to lead to a shortage. People routinely fire WWII and 50's cold war surplus ammo with 90%+ success rate. Modern ammo, if stored reasonably, like inside your average US home, will last 100 years.
Unfortunately, school shooters, while getting all the press, are an insignificant contributor to the gun death total. It's economically depressed young males with pistols that make up the majority of shooters, not people with assault rifles, 3 D printed weapons, full automatic guns, silencers or whatever else is the current scare theme is.
There's a real problem for the air force brass behind all this. Pilots are all "officers and gentlemen", drones are flown by enlisted people. Any large swing to more drones not only changes the combat environment, it changes the whole structure of the force. If you no longer have a large collection of ex-fighter jocks to staff your higher ranks with, the whole attitude of the air force as we know it will change in the long run.
If you'd actually read the article and followed up on the data, you'd have realized that the plasma level discussed (50 mymol) is achievable with the normal recommended vitamin C intake of 100 mg/day. This doesn't say anything about needing to supplement the intake heavily, it just shows one of the reasons vitamin C is a vitamin aka something we do poorly without.
Ye,s the RC plane will not take out an Autobahn bridge. But you start dropping bomb-loaded RC planes into a crowd in a confined area, lets say a Bundesliga game or a rock concert, and the resulting stampede will give you a huge damage multiplier. Or you start dropping it onto the speaker podium at some campaign event. Not every politician travels with his own personal flak battery. The idea of terror attacks is to create disruption, not affect war-like destruction.