Or find their place in the market alongside each other. There is no reason why smart watches can't have decent sales along with standard watches. A lot of people don't wear watches too so there is scope to attract from all walks.
I know you are convinced it will be total domination in favour of the smart watch, but sadly I doubt either of us will live long enough to see if a transition takes place. What sort of time scale are you expecting?
It didn't take a lifetime for smartphones to garner a total domination. Didn't most of us have a dumbphone before 2007?