How does “you guys” work in English? Linguistically?

Let us pause to really consider this possessive form for a moment: your guys’s. Though English is not exactly overflowing with case distinctions on its pronouns, case on pronouns is nonetheless surprisingly tricky, and it gets more so in the face of almost any degree of syntactic complexity. But still: your guys’s. Not only does [jɔrgajzəz] not exactly trip merrily off the tongue, it’s also morphologically weird. It seems to involve a doubly marked possessive, with not only the possessive form your, but also possessive “‘s” being pronounced as a full [əz] (for at least some speakers, myself among them) even though it follows a word (guys) that at least looks like it ends in the regular plural suffix -s.

(The arguably plural ending on guys is relevant because in other contexts the possessive and the plural collapse together in a convenient haplology—again: for at least some speakers, including me—so that the possessor in a phrase like “the horses’ tails” is pronounced as [hɔrsəz] rather than as [hɔrsəzəz].)

… this morphological car-crash of a form…

….

Some changes are hard, but necessary, because they require rewiring one’s grammatical system. Using they or neopronouns as nonbinary pronouns of reference fall under this heading. Other changes are both (comparatively) easy and have compelling reasons, like not using “mankind” to mean “humanity”, or avoiding crazy as an intensifier (i.e. meaning very), though I can personally attest that the latter is surprisingly difficult, perhaps because intensifiers are arguably functional elements and thus more deeply embedded in grammar.

Bjorkman tentatively concludes that, pending compelling evidence, “though I do try to avoid using you guys when speaking publicly to an audience whose linguistic background I don’t know, on balance I have not been convinced that the harm of you guys is enough to motivate the effort that would be needed to eliminate it from my speech entirely.”

Relatedly: Julia Evans’s 2013 “When is ‘guys’ gender neutral? I did a survey!” and Stan Carey’s 2016 Lexicon Valley piece in Slate, “How Gender Neutral Is Guys, Really?”.