Ah, I love Montana. Glad you’re getting out and about. I’m currently doing runs from SLC to LA and back. Hope to keep it going for a while longer. Need to see about an oil field job and make a bit more money to pay for a few dreams I’ve had for years.

Finished the book, could you tone down the grimdark a little bit? Please?

Grimdark? This book was practically slice of life. Or are you talking about the superplot?

The superplot, I suppose. Everything is 'fuck or die,' 'fuck AND die,' or 'fuck or we're all going to die.' Like damn, no one thought of doing a sperm bank via the cyborg peeps? Just to keep the monster and human population stable? Also, since humanity is on the outs too as someone said like 1/3 or 2/3 are all stillborn, so humanity is screwed too. And no one thought to setup some sort of gigolo service where the cyborgs selectively alter a group of volunteers (m/f) and cycle through them yearly? Sort of like volunteer harems or maybe selective service but for humans to breed monsters?

There was a book a while back titled something along the lines of, "Everything I ever needed to know I learned in Kindergarten."
It's true, mostly. I mean, I picked up keyboarding later but most of what really matters you at least get TOLD very young.
I say that to say this: when I was young I was an introvert, but when pressed I was not afraid to turn to violence to convince people that I was not to be fucked with, or made the butt of their jokes. After fighting I was punished, more than once, by being made to hold hands with the person I'd fought with for the rest of the day.
There were any number of punishments the adults around us COULD have gone with rather than the one that was most likely to result in ANOTHER fight, but they chose that one, and they did it to me more than once, as I said.
Why do you think that was?
WYLAMG? is that writ large.
You can feed the hungry by simply giving them food. You can shelter the homeless by building their houses for them. Doing that doesn't teach people how to feed or shelter themselves. You know what DOES? Leaving them exposed and starving until they learn.
THEN when they eat food they grew themselves, and live in houses they built themselves, they'll won't take what they have for granted.
Taken as individuals, everyone needs a helping hand at some point.
Taken as a race, humanity only learns when FORCED. Anytime something is handed to us, we fuck it up.
So I don't write about places where sensible people take control of everything else and MAKE people get along. That's boring and - to me at least - even more dystopian than the world I dreamed up.
Let people stumble and fight and fail. Let them face the long dark night alone and afraid.
Those who do and survive will be much better company than those who never had to fight at all.

That doesn’t make sense because your super plot has total irreversible population decline to total extinction across every single race. And the cyborgs can’t fix it. Literally nothing matters. The last expansion was just farm land that no one can live in 50 years ago. And there aren’t enough people period to keep the housing occupied in even the nice city along the wall… even WITH random monsters wandering into the city. There is simply not enough people left for civilization to continue to exist for much longer. First humanity will disappear and then finally the rest of the species since they can’t breed either for some reason. So total population in about 50 more years or so will be slimes, inbred goblins, and three vampires.

Ahh, but there are a few things you're missing (that have already been teased) and if I spotlight them here I spoil too much. But sure, that's one possibility.
In this case, inevitable disaster is in the eye of the beholder.

Okay so the vampires can turn everyone that they want to save, but that’s just another dead end. And I’m assuming the slimes are only doing well because they’re feeding off the bio waste of civilization. And remember you just had the one dude who was actually interested in solving the decline give it up for a gargoyle as apparently the only other option was to become a machine eunuch.

Those cyborg cultists sure have a winning strategy. Beginning to think they’re the actual villain.

Trust me. I didn't create WYLAMG? so I could write tragedies.
As a wise man once said, if you want to paint a beautiful picture, you need to use some dark colors.