According to Reuters, Apple recent purchased Akonia Holographics. And on their “About Us” page, they list their trademarked product HoloMirror which can project holographic media “to uniquely thin transparent smart glass lenses.”
In hindsight, this is the obvious area to go for Apple. Their Watch Series 3 is now a standalone cellular device, which earlier models were simply an extension of the iPhone’s screen.
Now the extension will be a pair of “thin smart glasses”.
It will be probably be a few years before we see or hear anything else. Apple holds their cards pretty close to their chest.
And Google Glass infamously went down in flames. So they’re going to make sure this product has the quality control it needs.