As I'm brand new to this forum and CX-5 ownership, AND I know this to be a five month old thread, I thought I'd pass on some real world info from what I've gathered so far.
1) Any commentary relating to "how other Mazdas from previous years are reprogrammed" is not exactly applicable here. I tried to have a guy do this, who was a "mobile key cutter." He had the right fob, but not the right software for the CX-5. He called his HQ and they admitted they didn't have it. He tried to use Mazda 3 software which didn't work.
2) You can buy re-manufactured (refurbished) keys off the "'bay" for about $80-$90 or higher. Those include uncut keys. I don't know yet if they already have programming from previous vehicles on the chip.
3) A local dealer said they would cut a new key and program the fob for about $90.
So, as of now, until the programming gets out in the market place for non Mazda guys, I don't know how you are going to get a replacement key fob (which I need) for much under $180. If anyone has successfully done a non-Mazda fob re-programming, this would be a great time to share that information.
FWIW