If they're taking money for it and selling it openly to the public then it's been released, it doesn't matter that the technology is labelled as being 'for development'. Were they to restricting sale to people who qualified as a developer in some way then maybe, but as it is most of these are finding their way into the hands of people who use them to play HL2, another couple of games, and then take up some space in the wardrobe.
Dev companies won't care too much, they'll take the $120 hit on a device if it's something they're going to make a lot more from. Getting the paperwork sorted to buy them may be more hassle, but most will do it.
A lot of the mobile games are written using Unity which allows C# to be used on all platforms, from mobile, through PC, and even consoles if you have the dev license for them.
The only issue with Unity is if you need the Pro version be ready to pay some serious money, but for a lot of mobile games the Indie/Free version is fine.
The use of the word drone to describe these is correct.
The Oxford English Dictionary includes the definition for a Drone as 'A pilotless aircraft or missile directed by remote control', a use that dates back at least to 1946 ("The Navy's drones will be..led—by radio control, of course—to a landing field at Roi."). There's no definition listed for a completely autonomous unit.
Some 360 degree cameras will be great for VR, but this one wouldn't. The vertical field of view isn't that great and it'd just appear as a loop round you rather than actually giving you the experience of being there.
Something like the Bubl camera would work a lot better, there you almost have a full spherical capture so the user can look up and down.
I think this'll collapse unless Sony decide to open it to PC and maybe other consoles. It's not something that is general-use enough to bundle it with every console they sell, and there's not been a truly successful aftermarket add-on for a console as game manufacturers don't include support for them.
I was supporting Oculus until the FB buyout, and then I looked to Sony as maybe they'd treat this as a general display device rather than a PS4-exclusive (You can plug an XBox into a Sony Bravia), but now I'm just hoping Valve wake up and Do Stuff with a few of Gabe's millions.