Even if they were interested in doing "one last run" of X cleats, those plans likely would've gone out the window with the pandemic. If much bigger companies with products that have much stronger demand are having trouble getting stuff made and delivered, how is Speedplay supposed to navigate that?
I also have trouble seeing them selling the designs, especially the X, to third parties because of the extreme similarity to the Zero, and for anyone who might have interest in producing X cleats (nevermind the whole pedal) the math of consumer demand vs cost to get production going is probably a nonstarter.