I think China is going to suffer an epidemic of infrastructure failure in the near future, perhaps as early as the mid-2020s if the 20-30 years estimate is correct.
For comparison, South Korea's extraordinary growth was followed by a series of infrastructure failures in the mid-90s. A relatively new bridge suddenly fell into a river during the morning rush. A department store imploded, killing over 500 people. Gas explosions all over the place. IIRC none of the major accidents in Korea were caused by low-grade concrete specifically, but there seems to be a general parallel between what the Chinese have been doing lately and the "build now, worry about quality later" mentality that Koreans adopted during their period of rapid growth. Both result in crumbling buildings 20-30 years later.
It's already happening. There are high-profile stories of bridges collapsing and so on. I live in Shenzhen right now and was looking for a new apartment during the summer last year. My roommate noted that a lot of the landlords all know that the apartment buildings will be replaced and rebuilt in 20-30 years.
If that's true, the expectation is already there. However, my impression is that this belief stems from this idea that construction will always be happening because that's how the economy rolls.
The question is what percentage of the population believes that this cycle really is the end game and what percentage of the population thinks they're investing into infrastructure what will last their entire life.
Most ordinary people either don't understand the cycle, or even if they do, they're powerless to do anything about it.
If what happened in Korea is any indication, the first generation of apartment buildings will be demolished after 20-30 years, homeowners will be "asked to leave" with as little compensation as the construction company can get away with, and a new block of condos will go up that the previous homeowners just can't afford. In Korea, at least we let the previous homeowners file complaints and protest for a while before we send in the bulldozers. In China, the bulldozers will probably go in first, and the GFW won't let anyone else know what happened next.
This is an accurate picture of what happens right now in China, but limited protests are permitted by homeowners to haggle the price. An extra complication is Chinese can only own their properties for a maximum of 70 years anyway, with many having only 30 or 40 years left on the state-granted lease, so even without the demolition cycle Chinese aren't really looking ahead more than a few decades anyway.
For comparison, South Korea's extraordinary growth was followed by a series of infrastructure failures in the mid-90s. A relatively new bridge suddenly fell into a river during the morning rush. A department store imploded, killing over 500 people. Gas explosions all over the place. IIRC none of the major accidents in Korea were caused by low-grade concrete specifically, but there seems to be a general parallel between what the Chinese have been doing lately and the "build now, worry about quality later" mentality that Koreans adopted during their period of rapid growth. Both result in crumbling buildings 20-30 years later.