Re: You will need
Well I'll happily stand corrected that such things exist and are affordable. However given that I've NEVER seen anyone use wireless earphones, while I have seen wireless headphones quite frequently - though still a tiny minority - I stand by my other point.
Taking an absolute number of users proves nothing. It's a tiny, tiny niche of the earphone market of interest to a very specific group of people.
Now that being said, one thing Apple are good at is making people decide that suddenly a pre-existing, barely used technology is desirable to the point we have the silly jokes about Apple "inventing" things. So given that BT earphones actually do exist I will also happily change my position on an iWatch to "cautious interest".
As a side question - I'd love BT earphones which were two separate parts without a connecting wire, so you literally just plug in each ear. Do they exist?