After looking at http://www.system16.com/ , I was thinking that Atari could have based the Jag off a board like the System IV http://www.system16.com/hardware.php?id=921 . It has a 68000 as the CPU and 2X TMS32010 DSP ( in some instances). It never made it out of prototype, but had two games:
The Last Starfighter http://www.youtube.com/watch?v=ghjjeZpoKLI and Air Race http://www.youtube.com/watch?v=TvYLCsmNKfE . Looks not too bad for 1993. I could see ports of IRobot and Hard Drivin' for this.
Or, what if the Jag's architecture was like the NEO-GEO, where the CPU had its own 64kRAM and the other four processors divided up the four RAM chips with multiple buses. http://wiki.neogeodev.org/index.php?title=Main_architecture What do you think?