Unfortunately I don't think there is that much money in the hardware and software. The car pc world is very diverse. If you get solid solutions that work for enough people to make it worth developing... you get a Pioneer Avic series unit.
It has cost me $100's and hours of time to develop my own micro controller and vb software to interface with RR that will do all sorts of stuff. I'm sure other people would be interested but probably only 5 to 10. At that point, the price point would be so huge nobody could afford it. This hobby IS for geeks... truth is the truth. Only reason I'm doing it is cause I can. This is in no way cost effective. I have to NOT look at dollars and time spent while I do it as the value would be astronomical. I just am filling that need for a fun project with bragging rights.
Like I said, I think you will see this "industry" move more towards all in one tablet/phone solutions as the majority and have a few stragglers who still run full systems for the reason that they can.