Thank you. I was just about to say the same. The iPod was the wildest success in Apple history at the time, completely obliterating any idea of competition, yet this is what its sales looked like:
If you were to measure iPod sales at its peak after the introduction of a new iPod and then measured it a couple of months before an expected announcement of a new iPod, you'd think that sales are tanking and that
Apple is Doomed™.
Apple Watch is about to have its best quarter ever. This is year 2 and I've already been seeing many of them out in the wild from non-early tech adopters. Give it one more release to really hit the mainstream. By Apple Watch 5, your grandma is going to be wearing one.