This assumes people really want to do that. Children are too expensive unless you have a lot of resources already. I think if costs of basic living keep increasing the future is increasingly childless for many people.
I'm 30, and I only know one person in my peer group whom owns a home, and he can only afford it because it's way out in the boonies. If people my age find things like home ownership out of reach, having children becomes a roadblock and therefore becomes undesirable.
Where do you live? I'm in Houston, a place with a low cost of living relative to California. I'm in my early 30s, and I know lots of people aged 25-35 who are marrying, buying homes, and having kids.
Well, personally I'm running a small online company. The company is basically just me, and it pays enough to support me. That means I can live anywhere without changing my income, so living where it's cheaper effectively makes me richer.
Oil & gas has a major presence here in Houston, and is a huge employer of engineers -- not sure about compsci people, but probably them too. The salaries are not as high as California, but the effective housing-adjusted salaries are probably higher. You can buy a nice 3+ bedroom house in a safe neighborhood for $200-400k. When, in California, Google giveth and the landlord taketh away, that isn't really money in your pocket (except you still owe taxes on it).
That's not really the point, though. Of course you can have children with nothing but a shirt on your back.
People want control over their lives, and this is one of the chief reasons why people want to own homes. They want to do with their property as they see fit, have a place to truly call "home", provide a sense of security, and have a place where they can raise their children under ideal conditions where a landlord can't just raise the rent or evict them.
When aspects of self determination such as ownership are removed, people become demoralized. If people don't feel a sense of agency, but can fill the void with artificial fulfillment like TV, games, food and "travel", the likelihood that they're going to want to bring children into the world is going to be diminished.
Of course, for much of history, people didn't own homes. The difference between now and times gone is people would choose starting a family in order to fill that void. But when there's plenty of "soma" for everyone, and people's dreams feel out of reach, what exactly is the incentive for the average person to have children?
Children pretty much remove control from your life one way or another. However, they do absorb the sum of who you are in many ways, and in that way they are an expression of self-determination as much as its remover. For example, I like to sing quite a bit, I lack talent so that ultimately doesn't impact my professional life in any way, however my kids adore my singing. They validate my self-expression in a way that would be difficult for me to get otherwise.
I do periodically feel a lack of agency from my kids and their needs basically controlling my life, but I also feel an immense sense of accomplishment for satisfying, or at least attempting to satisfy those needs.
People are unhappy when reality doesn’t meet expectations, and so if you grew up with the expectation that your children will grow up in a house and backyard and whatever else, and you can’t attain it, then you will be unhappy.
Technically, you can raise children in a war torn country, since it obviously has happened for many millennia. But with the advent of birth control, it’s much easier to choose.
People want to provide a stable home for their children.
Having to move can mean your kid has to find all new friends, and if buying a home is a complete impossibility for you, you might be further down Mazlowe's hierarchy than starting a family, and might have a life that's more financially brittle than you'd want it to be when you're taking care of kids.
This has been studied by sociologists and it basically comes down to people having more opportunities outside of the home to make money. For poor families, kids are viewed as an asset since you can use their labor to earn income through farming or other services. For higher-income homes, having a kid means you might have to reduce hours at work, miss promotion opportunities and so on. So people decide to not have kids.
There is immense pressure from most parents to have their children settle down and have kids. If that requires the parents to make financial contributions to enable this, that will increasingly happen.
This assumes people really want to do that. Children are too expensive unless you have a lot of resources already. I think if costs of basic living keep increasing the future is increasingly childless for many people.