Purely speculation here on my part, but just because Cliff has once said "its too much work" to do something like have two two sets of FW (for XL and mkII units) does not mean its never going to happen. In my years of Fractal ownership I've pretty much found that Cliff and Co. pretty much don't have the words "its too much work" in their vocabulary.
This is a man who will go and totally change things like the "mix laws" on the delay block at 3am on a Saturday night just because a user mentioned something Saturday afternoon . This is a man who already had an unmatched and class-leading product from its first version, and who could of easily sat back and just counted the money rolling in, and yet who who never let well enough alone, never felt it was "good enough", to the tune of what, 70 some updates and refinements ?
So yes, maybe two firmwares would be too much work, for most anyone else, or any other company. Maybe it just doesn't make good business sense to spend development time/resources making two versions so those with an updated product can still receive support, but maybe, just maybe, Mr. Chase will surprise everyone (which wouldn't be so surprising at all really) and say he just came in on Saturday and spent 17 hours coding an additional version like it was no big thing....
Sometimes I think Cliff has to say things are not possible, just to challenge himself to make it possible, because there isn't anyone else in this industry otherwise raising the bar.