By "over the drone" I meant what would followers add that the drone doesn't do already? Arguably you would expect a follower to be more useful than a drone, being more than a glorified portable storage chest. If there is no expectation of such then again I ask what is the point? Is there only one follower model with everyone running around with the same one? Are they customizable? Do they wear armour? Have skills?
The complexity is in no way minimal. The animations alone would be a large undertaking. The drone is able to hover along the terrain with no expectations of it looking natural. If a follower were to teleport around like the drone it would be completely immersion breaking and just look broken. There is a certain level of acceptable suspension of disbelief that comes with the drone not being humanoid.
The drone has been in development for, what, at least 2 years now? I'm sure it was a concept living in someone's head before that as well. Now let's say that drone tech can be reused for followers, maybe the timeline is halved? That's pretty generous. I can't see TFP investing a year into something that's not bandits, The Duke, a story, or general polish from here on out. I don't want to sound like a party pooper but I'm fairly certain we can expect to not see any new major features that the devs have not already discussed or promised in the KS goals.