Quite possibly the same that has happened to other OSes at MSR like Singularity and Midori: the team moved on to a new research project which involved writing another new OS.
I keep hoping one day such projects will have right level of management support and actually deliver something big into the mainstream.
We got .NET Native, async/await, W10 pico-processes, secure kernel,windows internal refactoring... out of those projects, but they still feel they could have been much more with the right amount of management support.
