The idea is to use a "unibody" process also called in one body, the same system that takes several years for the MacBook line of computers from the company, being taken now on a much smaller and simpler way.
For this would be used a method called "ultrasonic welding", which join two parts to make them appear a single through a polishing and cleaning of plastic once armed. But the "Ultrasonic" is due to how to make the holes for the sound output, because once pierced the material residues affect the sound and aesthetics of the product.
So they will use a coated abrasive material tool which vibrates with the plastic and through the magic of ultrasonics the earbud will be clean, smooth and well presented.
This is only the registration of a patent, no one will have to venture a release date, however, if Apple registered the intellectual property, there must be.