I get that drones are scary and stuff. But I mostly care about less military casualties. The fact is the military is adopting a lot of robotic tech that will reduce the need for soldiers on the ground or in the heat of combat. Besides, even with a smaller number our military will remain one of the strongest in the world.
They aren't scary, they are worthless. Drones are too primitive to replace troops on the ground. They are basically disposable.
Air Drones:
Look at Vietnam where thousands of bombs were dropped on both North Vietnam, and on suspected Guerilla positions in the south. The north was dirt poor and couldn't even make their own ice cubes, destroying a bamboo bridge over there was like knocking over a plastic chair. They just would just rebuild it in a few days and go back to farming rice.
As for the Guerillas, no matter how many you killed. More would just rise up to fight the corrupt southern regime or join the cause because their village got napalmed or because their crops got contaminated by agent orange. The same can be said for manned aircraft. You can't replace ground forces entirely with air assets, its been tried and failed.
Ground drones:
Watch them topple over or get stuck in some piece of micro terrain.
other flaws:
Most drones are controlled from bases in the US with dude sitting at a computer. Communications from the operator tend to lag for few seconds and feed back from the drone to the operator teds to lag as well.
In a conventional war, these drones would be vulnerable to an EMP. Contrary to popular belief, not all countries are equipped with stuffty downgraded exports and crappy officers and soldiers. You can't just fly over every country and drop some bombs and expect them to cave in as fast as Iraq. A lot of them have or are investing in next generation radar and air defenses.
Such defenses include:
Man portable missiles:
Tactical air defenses:
and Strategic air defense systems capable of downing cruise missiles up to 400km away