updated 02:35 am EDT, Wed September 12, 2012
New cable unlikely to be just USB 2.0 or Thunderbolt
As details have clarified on the forthcoming iPhone and peripherals, various outlets have started to take a look at the synchronization cable as well. The nine-pin connector could point to compatibility with a USB 3.0 connector, such as those found on newer Macintosh laptop models from 2012, leading to substantially faster synchronization speeds across the newer interface.
USB 3.0 is capable of in theory up to 5Gbps, slightly over 10 times faster than USB 2.0's 480Mbps. MacNN staffers performed some experiments, transferring a 20GB batch of MP3 and AAC files across USB 3.0 and also with 2.0. The USB 3.0 connection took 11 minutes and 57 seconds, while the USB 2.0 connection took 41 minutes and 8 seconds. While not matching the maximum potential speed, an fourfold increase in speed remains significant. The same cable would be capable of USB 2.0 synchronization as well, given the flexibility of the specification.
The nine-pin connector is unlikely to be compatible with Thunderbolt or FireWire 800. The Thunderbolt specification requires a 20 pin connector for both power and data transmission. While nearly all Apple laptops and desktops have a FireWire connector, the nascent iOS family of devices left the ability to synchronize with FireWire behind with the third generation hard-drive based iPod.
Of potential issue with a change in dock connector is accessory compatibility. The 30-pin dock connector has become ubiquitous with the "made for iPod" program started nearly a half-decade ago. There are persistent rumors of Apple-supplied adapters, but the compatibility of the devices with existing peripherals remains in question, at least until the announcement.