However in the modern world one reason drones work well is that the people the US and other drone-operating nations are spying on, and dropping stuff on, are hardly equipped to neutralize them. Short of shooting at drones with small arms and the occasional rocket launcher, they cannot jam radio signals or otherwise disrupt the command of the drones from their home base. This is hardly an issue with the enemies of today, but should one nation face another that also has advanced ECM technology, drones will become useless especially in a combat role.
The list of potential, technologically-advanced US adversaries is really short these days, but should something ever kick off in China (as if, but bear with me), manned fighters would almost certainly be used to fight for air superiority first. Drones would be reduced to surveillance and remote operations where the odds of it being jammed or shot down are low. True autonomous combat for drones is a pipe dream right now, but if something reliable that doesn't result in Judgement Day comes along, sure - we'll have drones doing ALL of our force projection for us.