It's really unlikely that an extra million spaces for housing would not change the current market price.
But EVEN if this was true that there is someone outside waiting to move back for when prices drop just a little, then now we have at least a million more people that can afford to live in a city close to their work, instead of being forced out.
More housing is better than less. There are no scenarios where it's worse for market price to build more housing.
> then now we have at least a million more people that can afford to live in a city close to their work, instead of being forced out.
This is one of the most underrated aspects of the housing shortage. Some of the people harmed by the housing crunch are people paying significant portions of their income in the form of rents. But most are the people who aren't able to move to economically dynamic metros in the first place, and are thus relegated to living in a place with worse job prospects. The latter group has no voice in housing policy, and is effectively disenfranchised in housing politics despite feelings its effects.
But EVEN if this was true that there is someone outside waiting to move back for when prices drop just a little, then now we have at least a million more people that can afford to live in a city close to their work, instead of being forced out.
More housing is better than less. There are no scenarios where it's worse for market price to build more housing.