[BrianG]

You know, since we are talking theoreticals here, how about this: Design the ESC so the FETs are pointing down. Then, attach an aluminum heatspreader that is exposed to the outside world. Then put four 3mm threaded holes at each corner. Attach an L heatsink or something as the default option (or not, whatever). This would allow people to alternatively attach it to the chassis or their own heatsink. Wouldn't involve opening the case that way. Just thinking out loud...