The worse I could imagine is that drones are used to catch people smoking pot in their backyards. The people who officiate over the police are elected officials and all their practices, including data retention from surveillance is subject to judicial review and the laws our representatives write.
Use of technology like this is inevitable anyway. It seems pointless to fight it, and if you do oppose it how would you fight it anyway? Write to you congress representative? Protest? Is that really going to work?