As per usual, some features from Samsung's newest wearable are going to be added onto the older ones. This year, the Galaxy Watch Active2 will be the first in receiving some features that the Galaxy Watch 3 has. This is in-line with what has happened in years gone by with other devices.
The Galaxy Watch Active2 Plugin app was updated on the Google Play Store recently - which adds support for Tizen 5.5. Tizen OS 5.5 is the OS that the Galaxy Watch 3 runs out of the box. We can assume that the Galaxy Watch Active2 will be able to get quite a few of the Galaxy Watch 3 features, so far, we don't have the changelog.
In the past, some of Samsung's older smartwatches - the Gear S3 and Gear Sport, have been receiving new features. These include Always On Display refinements, the Bixby voice assistant and sleep detection improvements.
Not only the Samsung Galaxy Watch Active2 is expected the get Tizen 5.5 support. It wouldn't be unlikely that the Galaxy Watch will get Tizen 5.5. After all, it is pretty young at the ripe age of two (as of last month). With the support, Samsung could continue selling the device without it becoming outdated.