New construction is like 1-2% of total housing stock annually. It'll take a relatively long period of time for these sorts of changes to hit prices because again, low price elasticity of supply.
edit: on slightly further thought, you'd also need this effect to either increase overall vacancy or reduce total construction, since any supply shift from occupied rental units to owner-occupied condos also implies a demand shift from renting to owning.
edit: on slightly further thought, you'd also need this effect to either increase overall vacancy or reduce total construction, since any supply shift from occupied rental units to owner-occupied condos also implies a demand shift from renting to owning.