Wow... Thank you. For anyone curious, this worked. Updating Rasbian tools packages provided new firmware needed for the image to boot on my Raspberry Pi3....
Thanks BuZz!
I also must say, that I like the new retropie setup script. With it, I was able to update the base install, then seperately update the underlying OS and Firmware.
Whats really great is that I am now on the 4.0beta, and my Xbox360 Wireless controllers still work perfectly (which they did not when I attempted a fresh install of 3.81)
Seems the new retropie setup script seperated the installation of underlying OS from the base install, while keeping driver updates seperate as well (giving you better choice of what gets installed)
Cool beans.