
The Apple Watch will be able to play music - yet it has no headphone socket - so it will have to be wireless.
Apple filed a patent for some bluetooth headphones back in 2012
http://www.cnet.com/uk/news/apple-looks-to-patent-earbuds-that-work-wirelessly/
So it’s reasonable to assume these are - largely - aimed at the Apple Watch. There are also a number of earphones coming out with lightning connectors - which would be able to charge a bluetooth battery as well as carry audio.
All the pieces fit.