This is a bad idea. Digilent already tried this with the chipkit products, and it hasn't done well. Part of the problem is a PIC is not an AVR, yeah that seems simple to understand but it needs to be considered before anything else. A lot of the arduino stuff doesn't translate well to the PIC and you usually end up with more code in the libraries just to make it work with arduino sketches, bigger programs, more flash usage.
What needs to happen is something similar to the arduino interface and boards but done for the PIC and not to be compatible with arduino in any way. It needs to build its own platform just like the arduino did. I know people will complain, arduino has shields you could use if you make it formatted like arduino !The shields are part of the problem. The pin layout isn't standard, the way the pins are grouped isn't optimal for the PIC and the shields often require libraries that don't work with PIC without a lot of extra code. Piggybacking on the arduino is not the way to get people started with PIC.