I hope Apple invests in the mobile apps and a web app before they spend resources on another hardware product. Fitbit's strength is what it does with the data the tracker collects-- Fitbit's mobile app and web app. Fitbit's data analysis and presentation make its tracker products best in class. If Apple catches up to Fitbit, Garmin, Microsoft, Wahoo, Jawbome, Nike, and the others in this area, than a band-type product could be nice. Apple could produce a strikingly beautiful band, but it would be a weak competitor without the mobile and web app support behind it.
Great things about WatchOs/iOS vs Fitbit, Garmin, Microsoft, Wahoo, Jawbome, Nike is all Apple need is open up more API, and there will be thousands of App creator eager to make money.
Personally, I think a waterproof BT bracelet included GPS with data logging & sleep tracking with data logging will be great, so I could use it only when run, swim, surfing, diving, jog, sleep,.... without AW with me, but it will sync with AW once it is within BT range of AW or activate from AW app, and charge it when I am not run, swim, surfing, diving, jog, sleep,... just use AW when bracelet is charging.
This way, I won't exhaust AW battery with GPS, GPS data logging, or sleeping tracking data logging. And it can be build with rugged rubber design for impact proof, since it will be consider an offline AW companion.
I don't think I want my AW become does it all, since I would prefer to have something rugged when run, swim, surfing, diving, jog, sleep,... and not have to wear AW all the time, also allow it to be charged during night.