I encourage people in the South to consider “th’all” for plual they. I will try “they guys.”
(Semi-serious suggestion; it’s what works for “you.”)
It’s “them guys.”
What about “youse guys?”
Hey! Youse talking to me or wha’?
Theyse guys, of course.
Or we could come up with a system like the one found in many Austronesian languages where there are 2 disitinct pronouns for “we” (me and you >< me and someone who is not you). And there’s no distinction between ‘he’ and ‘she’. It’s just one pronoun for all 3rd persons.
If we rework the paradigms, let’s make them both clearer and more inclusive.
Ahem… it’s “yinz guys”
I only lived in Pittsburgh until 4th grade but I still catch myself saying yinz fairly frequently here 40ish yrs later.
I’m used to getting misgendered on the phone because I apparently sound feminine on the phone. It annoys me a little but I just roll with it now.
I’ve never liked the ambiguity of “you” and I’m not wild about it spreading to “they”, but as @Chronos says, language evolves, and you don’t always get what you want. I am hoping that they-all catches on as the plural form. (I already generally use you all, despite not being southern, because the ambiguity bugs me.)
Anyway, it took me a few years, but I’ve gotten used to the singular “they”, and have stopped wondering who the other person is.
Maybe we should consider reintroducing an explicitly singular second-person pronoun in English instead of adding on yet another plural one? How does that strike thee? 
The button on my jacket reads “It’s not about bathrooms…any more than it was ever about water fountains — George Takei”.
To which I would add the observation that it’s not about pronouns. As @Darren_Garrison accurately points out, pronouns such as “she” or “he” are used when referring to someone in the 3rd person, not when speaking to them directly.
The “pronouns” conversation is all about raising awareness of the underlying issue.
I used to frequently get misgendered even before I started transitioning for that same reason. I have always had a somewhat high and feminine voice, so often when I would be on the phone or at a drive thru, they would call me miss or refer to me with female pronouns until they saw me or I corrected them. And even though I was actually a woman, because I was presenting as a man at the time, it would annoy me as well.
Now however, I’m glad I have the voice I have since it fits me as a woman much more than it did previously and makes it so I pass better. It also meant I didn’t have to go though any voice training like many trans women need to do, which frequently surprises them when they ask me about my training.