It does not have to be a sourceforge/ chdk style collaboration that our changes make it into the official release it could be for personal use and maybe have a community similar to what we have right now
Saying it's for personal use doesn't solve anything. For this to be worthwhile to Canon, the end result has to be more cameras sold. It's extremely unlikely an unsupported code dump would accomplish this. Quite a few companies have tried that in various forms, and generally hasn't ended up well for them.
I thought that canon made the firmware/hardware themselves so as far as I am aware there is no existing IP encumbrances.
We know for a fact they use H264 and exFAT, at a minimum. I would be very surprised if there wasn't more.
In reality, just going through a large code base and determining whether there are any issues would cost a bunch of money, and there's no way any competent legal department would let it out the door without that.
Even if there's no third party IP problems, they'd still have to worry about their own IP, and what if anything they want to keep secret. Plus they would need to examine liability and regulatory issues.
Honestly, if a company wanted to go this way, they'd probably be better off starting with an existing open platform and just adding some SDKs and drivers for their specific hardware. Writing some Digic drivers for Linux could easily be less work than open-sourcing their entire existing platform.
Sony makes a bunch of Linux based cameras, but the firmware is locked down, so you can't actually do anything interesting even though you can download the source. See http://www.sony.net/Products/Linux/DI/category01.html