The major shift comes because of the smartphone.
Previously to be homeless meant to be completely disconnected from society. No mailing address, no land line, you don't exist.
Today you can have a phone number and high-speed internet access without a permanent address.
This alone makes the prospect of dispensing with your digs when you can no longer afford them far less unattractive than previously.
People live relatively modern connected lives from vehicles and tents today.
I'm not speculating, I'm speaking from experience. I've lived a very vagabond lifestyle for years in CA, and this approach has really taken off in the last 5-7 years or so. Batteries last a long time, solar panels are cheap and efficient, prepay phones are affordable.
I used to spend a lot of time in various cafes around the SF bay area. The outlets at these places started becoming contended for by ostensibly "homeless" people looking to charge their smartphones.
In 2018 "homeless" people have smartphones, they watch netflix, they do all the things. The last time I was at Java Beach in the outer sunset a guy who just moved off the sidewalk into a van was playing 3d games on a gaming laptop using the cafe's wifi and electricity until closing. I know his situation because he told it to me. He was wearing pajamas getting some gaming in before they closed up to retire in his van down the street.
That's a pretty damn comfortable "homeless" life. It's not really much different than what people are doing in their $3k+/mo apartments he parks in front of. I don't know where he bathes though, there is the ocean right there in the worst case, right?
I'm not passing judgement. It just shouldn't be surprising, given these circumstances, that relatively sane and capable people are slipping into "homeless" lives. The severity has substantially diminished vs. the homeless of the past, especially places where the climate is nice year-round.
I think if there were no smartphone, these "homeless" people would feel much more motivated to relocate someplace affordable.
It doesn't bother me if folks are choosing to live homelessly someplace desirable instead of relocating someplace less desirable where they can afford a home. Apartments are overrated, where the weather is nice.