Though we are certain that the original Apple Watch, Series 1, Series 2, and Series 3

won't be because they aren't compatible with watchOS 9,

 The company has been releasing public and developer betas of iOS, iPadOS, watchOS, and macOS in July.

just after WWDC, for the past few of years.

This is all we currently know about watchOS 10

 including its anticipated release date

We've also made assumptions about which Apple Watch models