You keep the "reasoning core" burned and play the cat-and-mouse game at the I/O edge. Enemy invents a smiley shield, your R&D figures out some filtering step that defeats this effect without compromising general image recognition. Then the enemy figures out a new trick, your R&D invents a countermeasure, and so on - point is, this can happen for a long time in layers on top of the core model. If the enemy invents some robust way to attack the core that cannot be filtered out, it's game over for that hardware, but that is a much more difficult task and might take longer than expected service time of a given batch of drones.