Exact same thing is happening in my neighborhood - homes were “throw up” after WW II - quickly. And weren’t that big - (ours is 1600, but has an addition added on b/f we bought it).
These small starter home go for $1 million and up - and yes, it’s the land that’s valuable, not the home itself. A lot of them have old wiring, old plumbing and were poorly designed. I’ve had to have a lot of upgrades ($$) done since we bought the house.
When they are sold, inevitably they are razed and a much much larger home goes up in its place. Many are adding ADUs in the back as well - to either rent out or for elderly relatives.
Some are flipped quickly, others are kept as family homes. What we worry about are the now state-controlled zoning laws that mandate any/all property formerly zoned as a single-home property can now hold up to four units - more if it’s near a transit zone (which is all of the state of California) - then it can contain up to eight units. It will happen.
Here in Washington state I think they just did pass (or want to pass) a change in the zoning to the multi-unit thing. That will also mean an increase in the property taxes for the single home owner, because now their land will be even MORE expensive.
“But Mr. Tax man, I only have a single home on the property.”
“True - but you COULD have four housing units on it - so it is worth so much more now!”
All of the “conspiracy theories” about Agenda 21 - they aren’t just theories. Many cities (mine included) mention U.N. Agenda 21 in their planning guideline statements.