I don't know how capable this thing is. It's more an AR device than VR, and VR solutions like the Olulus Rift do need to be paired with a pretty powerful gaming computer. I'd have to see how well this would work for completely immersing in a VR world.
VR works on smartphones - you can optimise a game for a variety of different platforms. I could design a great VR game in Unity and then decide what platform to output it to - anything from an Oculus Rift down to a 3 year old Andorid phone with a Cardboard (obviously the lowest end version is going to have a lot of restrictions and limitations).
Hololens is going to be way more powerful than the current high end phones (such as Samsung note 4s which are already running decent VR) so this shouldnt be an issue.
My main advice to the OP would be to get Unreal Engine or Unity (free to start with) and start practising game design. We already know Hololens will work with Unity so this would be a good platform to start practising with. Also learning code would be important (eg Javascript or C#) to develop your game ideas, and probably some 3-d modelling package (eg Blender).
You don't need Hololens to design/create a game, and you can even test a VR game with nothing more than a decent Smartphone and a Google Cardboard.
At this stage just throw yourself in and start learning the basics so by the time the dev-kits are realeased you will have the skills to start developing for it.