| Gigabit Ethernet | USB 3.0 | 802.11n |
| Theoretical speed | 1 Gigabit | 5 Gigabit | 0.3 Gigabit |
| Real world speed | 1 Gigabit | ?? | 0.05 Gigabit |
| Installed base | Everywhere | Some PCs (not Mac) | Everywhere |
| Reliability | Proven | Unproven/Dubious | Unreliable in public areas |
| Cable length | 100+ meters | 3-5 meters | (50-100 meters of air, less with walls) |
| Wireless Extension | Possible | Not possible | N/A |
Gigabit Ethernet is a good decision. End of story.
Well when you put it like that... 
If they're smart they'll include power over ethernet (PoE+) so the camera can be powered as well as controlled over the single cable.
This spec looks like they want people to use a flock of cameras (what's the collective noun for these going to be?) all working together and sending synchronised data to a controller, without wireless latencies. There's a lot that can be done over a wire to provide guaranteed bandwidth that's not guaranteed over radio.