Asus has promised that it would release the Android Wear 2.0 update for its 2nd and 3rd generation smartwatches in early Q2 2017, but it took Asus until the beginning of Q3 to release the update.
The Asus ZenWatch 3 has already received the update in most markets, make sure to go into settings and check if you have the notification already.
The Zenwatch 2 has also finally received the Wear 2.0 update that includes a lot of goodies and a lot of optimisations as well as a complete overhaul.
There is a slight caveat though, only the 49mm Zenwatch 2 is getting the update, small thing to keep in mind for the time being.
If you can’t wait to receive the update on your much loved Zenwatch 2, users on reddit have already confirmed the existence of the update as well as they have figured out a way to force the update. Check it out here if you are interested. Note that the force update option will require you to flash and use ADB, so if you are not familiar with either of those, we recommend you to wait for the notification to arrive.