Wear OS, the OS made by Google, has been out for a long time and will come to watches as an update. Wait! The Wear OS update relies on hardware and not software. The only watch that will get Wear OS. The rest will stay on Tizen.
Back when all Samsung's watches were Android-based, the Tizen update didn't really care about hardware. The Wear OS does.
It's sad but it is true. You could have the best of the best watch, yet you won't get the update due to the hardware. Qualcomm even announced new chips that could assist devices running Wear OS run more efficiently, but most company's just ignored the new piece of hardware that could've granted access to Wear OS.
The stress that could be put on the components if it were to run Wear OS would be unbearable, as the AI wouldn't work and there would only be a couple of megabytes of memory left for the user to use. The other would be used by the system.
The old watches with Wear OS, if it didn't matter about how much stress would be put on the components, would be amazing and would reach their full potential.
Users wish for the new OS, and it won't come. It is a hard truth to swallow, but the Galaxy Watch 4, which is said to start at £399, will have Wear OS pre-installed. Everything about Google and their Wear OS just screams hardware out everywhere.
The bright side is that they haven't said anything about them not supporting the current devices out, so don't let your hopes get down!