The 2015 control system will be based on the NI
roboRIO, which has a similar architecture to the myRIO. I'm not sure what the level of support would be for running roboRIO programs and FPGA on the myRIO.
If the myRIO is not compatible with the FRC FPGA image, then I would expect it to be a lot of work to write a semi-compatible FPGA image.