It would encourage buildings to lower asking rents as vacancy periods grow longer, rather than having incentives to leave a commercial unit vacant, as with my p

It would encourage buildings to lower asking rents as vacancy periods grow longer, rather than having incentives to leave a commercial unit vacant, as with my proposal they'd already be taking a hit to valuation anyway as soon as the unit went vacant, and a new tenant paying 80% of the last tenant's rent is still much better than leaving it vacant longer while it decays through 70%, then 60%, etc. So overall the market would be more efficient, rents would go downwards more quickly in terms of CRE downturns, and you'd have fewer vacancies with more units reaching a market-clearing rate.