In America, rents have gone up astronomically. But this only happened rather recently, considering their housing bubble got pricked in 2006, and the tsunami of foreclosures took soooooooooooooo looooooooooong to even start materializing, it's still materializing, and not really up to full stream. But just in the last year to year and a half, rents have started suddenly spiking in key metropolitan areas Stateside.
So, if the same were to happen here, rents wouldn't spike at all, in fact, might just go down, especially for condo investors too scared to sell, and have to rent out their units and compete with thousands of other investors trying to do the same, similar to people trying to rent out their condos in Florida, and finding that they can't seem to find anybody to rent them out unless they drop the asking rents, because everybody is doing the exact the same, dropping their asking prices to score a renter.
But if the downtown lasted as long as it has in America, then expect after awhile that rents would then start going up, but that would foreshadow the bottoming of the free-fall and the beginning of a recovery.