There are developers working on Hololens stuff. All the incubation teams like LxP FUNction,etc were all revealed to be Hololens developers.
Granted, so far, all of them look to be small-ish incubation teams, so there's no expectation that they'll reveal some AAA Hololens games or anything, but they're probably the equivalent to Sony's London Studio atm, where they're the first-party equivalent of 'we're experimenting on how to make legit games with this."
Do we know the scale of those teams compared to sommit like North West Studios, the on Sony is establishing for VR stuff? Or are their team numbers still unknown?