The first dev kits will be available in spring according to wire. If we take Kinect as a reference, the revealed it first at E3 with short démos and concept videos, then showed the finished product one year later, and it reached the market a few months later.
So I wouldn't expect the thing to release before 18 months from now, but not much more either to fit in the "Windows 10 time frame".
I'd argue it demands a whole lot more development time for apps than Kinect ever has. They are pretty different