Back when the first version of HoloLens came out, Microsoft created a roadmap that highlighted several release points for the product. This isn't unusual, you start with the first device, second generation devices are typically smaller and more affordable and then with version three you introduce new technology that upgrades the experience; this is a standard process path in the technology sector. Microsoft, based on my sources, is sidelining what was going to be version two of HoloLens and is going straight to version three. By skipping what was version two on their roadmap, the company can accelerate version three which will be closer to a generational leap and help keep Microsoft ahead of the competition. My sources are telling me that this version of HoloLens will not arrive until 2019.
http://www.thurrott.com/hardware/90780/microsoft-accelerates-hololens-v3-development-sidesteps-v2