Well let's have a look at wearables, does the Fitbit have upgrades? What about android wear? Both of those have been in the market way longer than the Apple Watch. The apple watch runs a version of iOS same as the iPad and the iPhone, the bands are interchangeable. At the heart of a Rolex is a bunch of gears and a quartz, at the heart of an Apple Watch is a processor and ram.
The likelihood of your scenario happening with Apple's track record of putting devices on the legacy list, is about the same chance as a high school dropout with no family and 3 kids working at McDonalds buying a brand new Bentley Continental GT at 19 years old.
Regardless if you want to call it jewelry or not is beyond the point and the fact still stands that the Apple Watch is a
product made by Apple. Even if they wait 2 years to upgrade the watch, Watch OS support for the device goes out 3 years after the product is initially released and
Apple support will no longer work on the device if it is over 5 years old. It is considered vintage. Since the first watch missed support for pulse o2 and blood pressure readings, I'm comfortable saying they are going to release a second generation this year, stopping the production of the original Apple Watch and starting the counter for the 5 year legacy product support.
Apple may be known for it's great product support, but it is definitely not known for keeping a device's generation around for 10+ years. Even the iPod classic underwent changes throughout it's lifecycle. As for making comparisons, the apple watch is a lot closer to a computer in it's likeness than a piece of jewelry.