Firing squads should be making a comeback given recent Trump DOJ guidelines that break with what had been the precedent on these questions.

Perhaps this will turn into a test case that furthers Republican zeal for firing squads since presumably they are still obligated to kill her and it seems unlikely (as you point out) that a firing squad would replicate this same sort of failure, certainly not if they are also allowed two (times n firing squad members) shots at it if you'll pardon the unfortunate language.

The current administration has been quite open about its preference for firing squads. Personally, I don't find this reassuring at all but maybe that's just me. By the way, much of the US prison system is cruel and unusual in my view. I used to think prison abolition was a naive concept until I attended a talk were the speaker pointed out the same sort of conservatism was used to urge that prior abolitions, notably of slavery, were not only undesirable but almost unnatural. It seems much as Aristotle could not really conceive of a world without slaves, most people today feel prisons are simply a natural, necessary artifact of civilization. Of course, much of it is not driven by anything approaching a learned Aristotelian principle but rather a sort of vicarious satisfaction in meeting a violation with a greater violence.

The truth is the American prison system is largely barbaric. As usual the current president is less a sea change and more an unvarnished look into the prism of horrors that is the right-wing American mind.