Is any part of the diagnostics port magnetic (like magsafe)? Is there any way to tell if power, rather than just data, is able to transfer though the port? If so, it would definitely point towards future smart bands. Sure, a smart band could have it's own battery supply that doesn't connect with the watch, preventing it from leaching precious battery life, but then you'd have to charge two separate devices (band and watch) every day. If power could transfer through the diagnostics port, then not only could you have battery packs in smart bands to help power the watch itself, but also you'd only have to charge one device each night (the watch could then recharge the bands).