Apple has documented in detail how to deal with legacy formats that use outdated compression technology. Cineform is one such codec. You can convert your master files for use with upcoming Mac OS versions but unless the manufacturer (GoPro) supplies third party support for Cineform, it will not be recognized by either FCPX or Motion after this latest release of Mojave. Here is the complete Apple document which explains this and also lists all legacy formats that will be affected:
Thanks for your reply. I have read and understand about Apples move away from cineform. I have just been looking for info on when this will be implemented in OSX as I haven't read much more about it since Apple warmed customers about the "legacy formats" that will no longer work in future releases of OSX. In the short/medium term I will not update OSX and continue to use the GoPro footage with my Mac/FCP.
I assumed there would be more talk about this for the GoPro owners who use Mac. Guess not