Virtually all drones will be equipped with varieties of cameras as a part of their sensory array to ensure that they don't crash into buildings, birds, or each other, as well as to be able to provide visual feedback to the pilot, either in real-time or uploaded to a central server to access later - or most likely both.
Naturally, the idea of a bunch of flying cameras is something to get privacy concerns riled up, and rightly so. Though she overreacted a bit, Seattle resident Lisa Pleiss can't be faulted for being suspicious of a drone that was hovering near her 26th floor apartment, especially since she was in the process of getting dressed.
New technology is often scary; we don't know what all it can do, and usually one of the first people out of the gate is a myopic dumbass who doesn't know his hole from an ass in the ground that threatens to ruin it all for everyone.
Drones, despite the very obvious Big Brother implications that they carry, don't have to herald the destruction of personal privacy. In fact, Betteridge's Law aside, their misuse can be reined in with some pretty simple measures.
Extension Of Aircraft Registration
If there's one thing the Internet has taught us, it's that anonymity is a major factor in dickish behavior. If people feel they can act without fear of repercussions, the desire to be a jackass is orders of magnitude greater. This one is easy: we simply expand aircraft registration to include any drone that comes mounted with a camera. Though possibly problematic on really small drones, requiring all drones to be emblazoned with a high-contrast, easily visible registration code that is tied to a specific individual or organization will be a major roadblock to most casual peeping toms.
While this would still allow drones to reach the tops of most buildings it would keep them within eyesight, as they wouldn't make it halfway up taller buildings in major cities like San Francisco or New York. While not as directly effective as a registration number, the two combined raise the barrier for privacy invasion even further.
Harsher Penalties For Violations
No matter what roadblocks and deterrents are put in the way, there will always be a few someones that will try to get away with shenanigans, so this last idea is applicable to those. Due to the greater ease with which privacy rights can be violated with drones, when someone is caught and convicted of a willful violation of privacy via use of drones or drone technology the punishments need to be harsher than what current penalties may be. The crime simply needs to not be worth the risk.
The Simplest Solution
Something that needs to be remembered amidst all of this is that we live vulnerable and open lives on a daily basis in any case. I don't mean that as a scold or as a warning, just that the manner in which most of us live our privacy isn't made much more vulnerable by the presence of drones. Drones do make it easier to spy, of course, so that threat is greater and should not be dismissed out of hand, but there is little they do that can't be accomplished by a photographer with some inventive angles and a strong enough lens. And just as with the peeping toms of old, there is a simple and extremely effective way to thwart their endeavors.