This was just released from Jared Spataro, general manager for the Office marketing team:
"Over the last 12 months, we’ve transformed Office from a suite of desktop applications to a complete, cross-platform, cross-device solution for getting work done. We’ve expanded the Office footprint to iPad and Android tablets. We’ve upgraded Office experiences on the Mac, the iPhone and on the web. We’ve even added new apps to the Office family with Sway and Office Lens. All designed to keep your work moving, everywhere. But that doesn’t mean we’ve forgotten where we came from. While you’ve seen us focus on tuning Office for different platforms over the last year, make no mistake, Office on Windows desktop is central to our strategy.
In March we introduced an IT Pro and Developer Preview for the 2016 release of our Office desktop apps on Windows, and now—as a next step—we’re ready to take feedback from a broader audience. Today we’re expanding the Office 2016 Preview, making it available to Office users everywhere in preparation for general availability in Fall 2015.
Office 2016 previewers will get an early look at the next release of Office on Windows desktop, but more importantly they’ll help to shape and improve the future of Office. Visit the Office 2016 Preview site to learn more about the Preview program and if it’s right for you."
Instructions to get preview - https://products.office.com/en-us/office-2016-preview