When Microsoft uses the term “Mixed Reality” it does not mean AR. They mean the support for both AR & VR. This vid covers their roadmap. What is interesting is that they are making their sophisticated inside out position tracking and obstacle monitoring hardware chipset available to people who wish to partner with Microsoft to develop lower cost VR and/or AR head gear. This is exciting as it opens up a lot of competition and forward movement in HMDs.
Details here: inside-out tracking at 00:27, user h/w requirements at 37:00
They are embracing a wide range of lower end hardware.