Let's take Max Busser as an example. Max Busser describes his MB&F watches as 'machines' and as wearable art. A smart watch doesn't replace our desire for one of his watches by virtue of its utility. Those who find Max's art compelling will continue to do so, even if they also find a smart watch compelling.
We don't 'need' our watches. We 'want' them. The question, really, is does a successful smart watch launch by Apple, or anyone else, make us want them more, or less. I suspect the answer will be more.
Best,
CaliforniaJed