I’m pretty sure that Kim Kardashian starts many of her Tweets with “OMG, you guys!” to her 51.3 million followers. I’m also pretty sure she has a mix of men and women in there. So I think we’re ok.
As a born and bred east-coaster, we’ve said “hi guys” for as long as I can remember speaking (at least 35 years) and it has always referred to a group of both boys & girls or men &women.
“you guys” has been in the vernacular for a long time. It’s the “dudes” and such that seems icky.
I’m in agreement that “you guys” can often reference a group of mixed gender. But no, I’ve never heard anyone say “I saw a guy today wearing the most incredible pumps.” Or anything like that when referring to a female or group of only females.
@Nrdsb4 We say “hey guys” to a group of only women all the time. I agree it doesn’t work, however, if you’re referring to one person - as in your example.
Agree w/ @jym626 re: guys and dudes. No one not named Jeff Spicoli should ever use “dude”.
@Fishnlines29, yeah, that might happen. But would you say “these guys came into the bar” referring to, say a bachelorette party? I wouldn’t and haven’t heard it used that way.
“Y’all” is one of the words I miss most from living in the south. It’s much better than “you guys,” but I quickly learned I couldn’t say it up here without being teased. I particularly love it when people say, “Let’s go to you guys’ [pronounced ‘guys-es’] house.” Sigh.
Go to you guys’ house…that sounds funny to my Texas ears.
@Nrdsb4 No, I wouldn’t. I think there’s something different about referring to a group directly in front of you: “hi guys!” when the women you are addressing clearly understand they are women versus speaking to a friend and referring to a group as a third party - it would then be unclear.
Folks (see what I did there?) - maybe we’re getting off-topic? 
So what?
I know. I use “folks” all the time. Probably obnoxious to someone.
What did I start here? Sorry. I didn’t think we’d go on this track, so may have edited out extra comments. Eg, that I also say, “Are you guys interested?” But I don’t refer to all of you here, as “Hey Guys.” Or at least, I’d think hard about it, want to think the group is familiar enough to do so.
And I do love “Y’all” and “You All.”
In the end, maybe saying Dude isn’t so different than, “Oh, Man.” But it sounds like teen speak. And I can think of other words/phrases that, despite being “common,” aren’t so great.
But I can stop here. I said the kid who did it was quite nice.
There are some occasions where “dude” is entirely appropriate, I think. Like yesterday, when I was sitting at an intersection and two cars narrowly missed t-boning each other right in front of my car.
“Duuuude” was about all I could manage to get out of my mouth. I have no idea of the gender of the idiots involved, btw.
Annoying is when y’all has the apostrophe in the wrong place, especially when it’s used by southerners who should know better. But I have apostrophe issues in general, so there is that.
My S19 likes to say “Look at this dooooode!” whenever I enter the room wearing something ridiculous…which is pretty much every time I enter the room. But I digress.
@MotherOfDragons, I am guilty of “ya’ll”, “Give me a break…Dude”
My lifelong-New Englander 15y.o. uses “y’all” in place of “you guys” in a deliberate way to be gender-inclusive. It wouldn’t surprise me if this becomes common, as with the use of “they/them” as a singular pronoun.
^ That’s where “yinz” comes in for us Pittsburghers. 
would it be annoying to point out that this whole guys/dude thing is extremely binary gender-normative?
@Consolation During the 90’s, people started using the word B * T C H to refer to any gender that originally applied to females (dogs, that is before - unfortunately - specific to human females). Then, of course, that changed over time to the more subtle nicety, Beyotch!
I find this side-topic very interesting as it came up in conversation with my wife and friends a few weeks ago. I’m from Northern California originally (NorCal to me), but have lived in Southern California (SoCal to me) for the last 30 years. But those originally from here never referred to Northern California as NorCal, nor use SoCal or CALI at all in their language. My wife, from the South Bay (south of LAX and west of the 405 freeway) is from Torrance. She has this country twang in her voice and uses the term Y’all. Her mother can’t explain to me where she got it from. My brothers, who still reside in Northern California, call this area L.A. whereas I take offense to that because I live in Orange County. I still use the terms “Dude” and “Bro” when referring to males only. I haven’t used “Chicks” in like forever ago. But I definately use “Guys” when referring to a mixed group. When it’s a group of females, I use “Ladies”.
Again, this is all very interesting 