It'll probably never happen unless one or two talented people are REALLY dedicated onto getting it work.
The gdrom disc is a special compression cdrom that can hold a full gig of dat ainstead of the regular 750 megs.
The cgdrom has 30 mb at the beginning that is in regular iso format. That can be read easily. Then there is a physical barrier (a black line) between it and the cgrom format data, which cannot be read by a normal cdrom. Now in theory a cdrom can read cgrom data, but as it doesn't recognize the data, it'd have to be raw read. This would require a custom cdrom driver. Also it most likely means the gdrom would have to be cached to the harddrive durning gameplay anyway, so it's pretty pointless.
There are rumors of certain cdroms that can read cgrom discs, but so far nothing real has turned up.