Calling it now, in ten years "y'all" will be a standard fixture of every American English dialect and nobody born after 2020 will bat an eye at it. It's just a great word, distinct in semantic utility and satisfying to enunciate. Even as a Pittsburgher with a license to "yinz" I still say "y'all".

Agree.

“Ya’ll” is linguistically necessary in English since the word “ye” was deprecated.

A common alternative to remove ambiguity between singular and plural “you” in some parts of the US is “you guys”.

English has "thou", which was the singular second person pronoun, and "you" which was the plural second person pronoun, but also used as a more formal, polite singular second person pronoun. Through a kind of formality inflation, everyone started using "you" all the time and abandoned "thou". Contemporary standard English doesn't have a plural second person pronoun, but needs one, and so "y'all" (or "ya'll") is being used now in some regions.

“Ye” is just the nominative case (like “I” vs. “me” being accusative), it has nothing to do with number. Thou/thee is the one with number.

You have it exactly backwards. Thou is singular and informal, ye is plural and / or singular formal.

Ye is a second-person, plural, personal pronoun (nominative), spelled in Old English as "ge". [0]

The word thou is a second-person singular pronoun in English. It is now largely archaic, having been replaced in most contexts by the word you. [1]

[0] https://en.m.wikipedia.org/wiki/Ye_(pronoun)

[1] https://en.m.wikipedia.org/wiki/Thou

Not sure how my comment is “exactly backwards” — it’s logically consistent with your (new) comment. My point was that, relative to you, ye makes a case distinction (nominative), and that relative to you, thou makes a number distinction (glossing over formal/informal).

We deprecated ye and thou, but it’s the latter that “requires” y’all, because only thou (relative to us still having you) distinguishes the number of people.

Edit: put another way, “thou/thee is the one with number” meant that reintroducing them would create a number distinction.

Then, there’s all y’all.

Also a Pittsburgher and I find y'all and you guys to be much more natural and widely applicable than yinz.