The parent's point is that as something becomes more and more scarce, the price will increase. As the price increases, fewer and fewer projects will be able to

The parent's point is that as something becomes more and more scarce, the price will increase. As the price increases, fewer and fewer projects will be able to justify its cost, leading to many to have to find alternatives or not be built at all. To take it to the extreme, as price continues to rise further, at some point there will be no project that creates enough value to justify the cost of concrete, at which point it will "no longer be needed". He is not dismissing anything, just pointing out a simplified rule of economics.