Farmers (really the poor/underclass) directed o T3/4+ surplus that aren't worth $$$, where RE price declining. Also see central gov recently spending 300B rmb (imo just start) to transition vacancies into social housing. T1/T2 vacancies for more affluent/educated gen. Hukou likely self correcting problem (they'll keep reforming), lots of education surplus resources =going to free up YoY relative to trend of decline in past births. It's a big challenge - but IMO it's a easier problem to fill housing when you already have it then try to build enough housing when you don't/can't. Broader urban policy - central gov trying to distribute growth, urbanize/move ppl to less developed interior 2 tier cities with higher % vacancies with new industries. Big coastal hubs likely has soft upper bound in population (look at post 2014 population stalling for big T1s), I'd expect them to slowly settle 10% higher where they are by soaking up surplus to leave vacancies at healthy range, higher than 5% in hot western markets, lower than 15-20% in PRC. It's definitely a hard problem, but it's a problem where most of the physical pieces are are there.

>The construction techniques they use to soak up unskilled labor results in concrete buildings that will only last 20-30 years.

Unskilled gets trained by skilled, and do not remain unskilled. Bulk of building stock was built in last 15-20 years by migrant construction lifers already with 10+ years experience (entire demo skews old) with a lot of concrete pouring and steel welding experience. You don't build as much as PRC and have unskilled construction workers, half the world is built by diasphora migrant workers drawn from even less developed countries.

TLDR on China collapse meme narrative of PRC construction, for what it's worth my previous field. The chinese buildings have 30-40 years life spans (no one credible guestimates 20) narrative conflates PRC construction standards in last 20 years, where vast majority of new building stock was accumuluated, and is fine for 50-75+ years (as in the concrete structure is durable), with not affluent at the time PRC choosing to cheapen out on building systems that can be easily retrofit up to modern standards. TLDR is concrete/structure/frame is FINE, "short" lifespan is really about shittier/lower quality mechanical systems, not ecological, expensive to maintain etc, and until recently because PRC so good at building fast, the answer is just to tear down and rebuild. Now PRC richer, can still choose to rebuild or retrofit (both of which they're still good at), new HVAC, facade etc, to meet performance standards now that vastly richer. This got twisted into PRC concrete last 30 years. Quality of towers being put up in CAN are comparable (and frequently worse) as stuff I see in PRC where the entire process of erecting hires has been optimized to death.

There are some legit shit tier construction pre 90s (and much older) builds, i.e. all the gross mid rise you see in left behind township/village level admin divisions, exactly the kind of bad/poverty building stock reaching end of life that urbanization drive is designed to move people out of (stuff that's still all over SKR/TW). But even then, they're not collapsing out of nowhere in any numbers that actually matter, other than in event of natural disasters (i.e. Sichuan earthquake scandal), which is a real consideration, in some geographic areas. But most of building stock, built in last 20 years after - again we're really talking about the frame/structure - are fine for 50/60/70+ years like west. Also important to note vacant towers mostly not abandoned projects, there's still basic maintenance happening because they're on someone's portfolio. They're not sitting derelict for 10+ of years getting killed prematurely by elements -> they're not going to come falling down. Yes some will, but rounding error.

Regardless, IMO broader consideration is RE surplus was 1-2% of GDP for ~15 years where boom was happening. Even if they sit idle/unproductive indefinitely, you're looking at in aggregate ~1 quarter of misallocation at current GDP over ~60 quarters. That's not too bad of inefficiency relative to how much was built, and inefficiency of too much > too little, especially when any solution to urban housing / infra congestion starts with having enough.