Well they came up with GX really quick... And it was really designed so that Mazda could come back and compete as the rx8 has gone bye bye.
Then the merger happened and everything is up in the air.
The rules package for 2014 or at least the exact classes is to be announced at or before the 24 hours of Daytona in January.
To race the Z in GX .... a new car would have to be made , tested and developed ...this equates to $$$$$$$.
I can say this.... There is hope for something. Stay tuned