If there's a real market for Kinect development tools, Microsoft will sooner or later own it, exactly the way that they own the C++ development tools market on Windows, Zune, XBox 360, etc.
It would make a lot of sense for them to release something like what you've developed for free. After all, if it pushes up Kinect sales and locks developers more tightly into the Microsoft ecosystem, Microsoft will want to do it.
Even if they don't want to release the development tools for free, I see no reason why they should let you access their hardware. The next version of the device could easily have a locked-down, encrypted communication channel. Look at how hard Microsoft tried to prevent the various XBox iterations from getting hacked. They even went so far as encrypting the buses that ran inside the device.
If you really want to work in this area, build your own hardware and make it a truly open platform. However, be prepared for attacks from a known patent troll.