Developing in Vancouver is outrageously expensive. Its voters chose a lengthy approval process for new housing. High housing costs are a political choice.
At some point the market would flood and there wouldn't be as much demand anymore, but if every single person in Canada wants to live in Vancouver everyone is in for a world of hurt until Vancouver has 30 million dwelling units.
The building of dwellings has outpaced immigration so that alone is unlikely a silver bullet.
Several years ago I was living in a lovely, historic, but no-frills apartment in a desirable area (Cobble Hill, Brooklyn) when several new “luxury” apartment buildings opened nearby, all around the same time. They were only a bit more expensive but offered lots of amenities (doorman, elevator, gym etc) that my building didn’t have.
The impact was remarkable: when other apartments in my building went on the market they sat unrented for weeks, when they’d previously rented in hours. The landlord actually lowered the rent on them! In NYC! Our lease was up soon after, and we managed to negotiate that they gut renovate our kitchen in exchange for extending our lease.
Not to be a doubter, but it seems like this note completely changes the context of the problem they stated. A slightly more expensive housing is competitive with the current housing you had. A higher-end luxury building being built costing 10x as much would likely have different effects.
Adding one home at the top of the price range, increases the number of affordable homes for someone, somewhere, by at least one.