Yes, the "technology" allows for this, and much more. Most drones even in the hobbyist range have GPS options and doing straight-line autopilot and multi-waypoint settings is not that hard in the grand scheme of things.
I still don't see where drones have much practical commercial application in the sense of them becoming some kind of regularly used device and/or PTZ replacement.
I could see them used at temporary events or at facilities that have the budget to cover the cost of owning/operating such a device. It will be a niche market for sure. Far more smaller than the market is currently for PTZ cameras.
Motion sensing activation could be used to launch drone in areas that cannot be reached by PTZ limitations and or stationary cameras. Secom in Japan is currently developing technology testing drone response to alarms then transmitting live video to a Central Station on home network.
Absolutely it does, see DJI Lightbridge with Groundstation for rotor based UAV application:
DJI - The World Leader in Camera Drones/Quadcopters for Aerial Photography
One of the biggest limitations though is flight time per battery (dependent on weight of UAV load).
I understand this is not approved by the FAA for commercial use yet.
It's unclear if the OP is located in the US, but the FAA presents fairly well organized information, staring with a brief summary here which confirms Undisclosed B's understanding: Unmanned Aircraft Systems (UAS)
A broader summary of FAA UAS policies can be found here: Unmanned Aircraft Systems (UAS)regulations_policies/
If you're talking about a Business Campus type of situation, I would think a system like the Skycam that the NFL uses would be better than drones. You could get a better camera on that system and it would have way better stablization. You could mount the system between tall buildings or tall poles/towers and have multiple systems. SkyCam
SkyCam in Action