Alas, nothing can replace it (yet)
My Pebble Classic (!) can do:
* Time/Date (with many watchfaces) * Calendar * Weather * Stepcounter * Sleep tracker * Alarms, Timers, and Stopwatch (smart alarm for sleep, other ones useful in the kitchen) * HRM (via SimplyHRM or Strava) * Running/bike tracking (native or e.g. w/Strava) * Music control (Spotify, awesome during sports) * Google Maps support (also with navigation) * 2FA HOTP * Oh, and notifications (w/filters) * With recharging once a week. Which also means the battery is gonna last, unlike those watches who recharge daily. * Works under shower, too. * And all this, for the price of ~100 EUR (a few EUR for some of the above apps).
My Pebble had the dreaded graphics issue. Pebble 2 has build-in HRM, but it isn't as accurate as my Polar H7. Pebble 2 has a crystal clear screen, the design looks more professional, and the wristband is better than the previous iteration.
The only thing I've never quite been able to set up, is managing a shopping list for in the grocery store (just with the ability to flag what is done). I miss such a feature so much! Using my smartphone for this is a ticking timebomb. One day, a kid is just gonna bump into me and poof its gonna drop on the floor. Won't happen with a smartwatch. And that is a use case right there, one no other device than a smartwatch can fulfill.
I admit, smartwatch use cases right now are niches, but that doesn't mean they're irrelevant. Plus, in The Netherlands it is going to be illegal to use a smartphone on the bike. A smartphone is far more safe, and it won't drop. Being attached on the wrist has a clear advantage for use cases like these.
One disadvantage is information leaking. Although smartphones are also vulnerable to that.
But I'm not sure how they manage to claim a 5 day with a color LCD display, I guess I should add the "always on display" to the list of pebble features I used.
* Telling the time
* Tracking my activity level
* Tracking my sleep
* Timer and occasionally a smart Alarm
* Letting me see my motivations without pulling my phone out.
* changing volume/track on spotify.
The fitbit charge 2 has most of those features, the main thing it's lacking are timer, smart alarm, spotify control and the more advanced alerts (apparently it only does text/calls and calendar). All those missing features are software features rather than hardware features, I kind of expect fitbit acquired pebble so it could get some of that technology.