I don't think anyone thought dumb watches would die. But I think it would be foolish to think there won't be a dent in the market.
It's entirely possible to think that the sub $1,000 watch market, and certainly the sub $500 watch market will be on life support in the next 5-10 years.
I still think once we get used to a phone on our wrist, why would we go backwards to wearing a dumb watch?