Some companies will replace your defective item under warranty with a factory refurb. Dell does this with monitors and Seagate does it with hard drives, to name just two.
I don't know if Apple does this. As they're not selling the Apple Watch line (what some people refer to as Series 0 or 1st Gen) those unsold could easily serve as warranty replacements.
When those are gone, Apple might use factory refubs for warranty replacements. I don't know if that's their policy/practice. If not, then with no Apple Watches left, you'd get a Watch at the same price tier as you had, the closest model being a Series 1. Apple did this all the time with computers, both desktop and notebooks. But at this point I agree with Garz- you'll get another Apple Watch 1,1 or 1,2 like you had.