Similar to the idea behind Google Glass, HoloLens is a wearable visor, but it takes AR a step further by enabling the projection of holographic images onto the surrounding environment. Of course, AR mustn't be confused with Virtual Reality, where the viewer is fully immersed into an entirely new environment.
That said, for control purposes, AR could possibly seen as a more suitable immersive technology compared to Virtual Reality, as the holographic image looks as if it is projected onto a real surface, in this case the DeepMind 12 synthesizer. This enables the user to explore parts of the synth that the knob- and fader-encrusted interface just can't touch.
This is the first time we've seen Augmented Reality deployed in this way within the music tech industry, but it was only a matter of time given the developments with music and VR that are already happening.
The news of an AR interface and the announcement of a possible rack version in the future might sound a bit ambitious given that Behringer's DeepMind 12 is yet to be released, and there's currently no word on when it will hit the shops. However, this low-cost poly is on its way.