"A drone would take 10-20 minutes to cover such a distance" The strategy would be swarms of drones, who hibernate somewhere in enemy territory and gets activat

"A drone would take 10-20 minutes to cover such a distance" The strategy would be swarms of drones, who hibernate somewhere in enemy territory and gets activated once needed. Also, you can have different propulsions, so in the end, basically have smart amunition/rockets. But like I said, so far the artillery is not going away anytime soon.