There's also the question of their role: while "power users"'ll make up little direct contribution to Apple's haul, they've forced Apple to expedite the usual inscrutability at times: Apple's been fairly quick with the reassurances after the dual (perceived) fiascoes that were the half-done rehaulings of both FCPX and the-suite-formerly-known-as-iWork.
The question then becomes whether a variable amount of scorn'll sufficiently tarnish the Mac platform as a whole, and whether it retains any inertia to overcome any blip in opinion; that'll depend on what proportion of Apple's Mac owners do care - that hasn't been established specifically for the Mac itself. But it's fairly easy to project along the lines of your note on Apple's dependence on the consumer when accounting for all business: no doubt adoption rates during the past few years've been up to the halo effect, and we only need decide whether the proportions line up - the power users, after all, have always remained, by definition, a minority; they've thus always had a disproportionate amount of influence.
But you're arguing just as well for simply getting rid of their business selling computers: perhaps they could just as well play that chance and feel all the better focused for having fallen into the second. I'm sure there's a surprise within that mold happening within Apple's future; it'd at least give the analysts an impression of sufficient prescience. (Or they'd grant the issue sufficient apathy on that front solely on the basis that their computer lines have reverted back into one of their self-proclaimed "hobby" niches - half the fun of Kremlinology's in tossing away the assumption that every actor must constantly execute, chop-chop.)
(Which takes me back to your first - I do understand that both App Stores don't even so much as consider OSS licences: precisely my claim that "I doubt open-source developers were paying to have their executables codesigned in the first place".)