They will be "banned" by the major powers who can afford sufficient defenses against them (US, Russia, China, etc), with periodic "terrorist" strikes by "unknow

They will be "banned" by the major powers who can afford sufficient defenses against them (US, Russia, China, etc), with periodic "terrorist" strikes by "unknown actors" with a pattern of only mild convenience to said major powers. Meanwhile these powers will maintain strategic reserves of the drones only ever used for training. That is assuming there remains any defense against these drones by new or conventional warfare. This might be a legitimate threat to major military forces themselves at some point.