1) If you expand housing, demand will go up. People fill jobs, and add demand for local businesses, enable growth in exporting businesses' headcounts, creating more opportunities for others.
2) If families can afford to live somewhere dynamic, then many of their children will want to stay, increasing the population.
My point is simply that noting that 500,000 new homes could be created is important. But even better would be a guide to how growth can continue, density can continue to go up, in an orderly, practical and aesthetically acceptable way.
Otherwise you end up with the same problem a few years later. (Or more likely, you never actually solve the problem even temporarily. Because the housing growth doesn't keep up with demand growth.)
The reasons for this is density itself is valuable. So dense places either get very expensive, or keep getting denser.