[flar]

This is a 1950s idea. Almost every city did this back in the day, and some are now converting back to 2-way.

It would be less detrimental to businesses on Yonge than it has been in other cities because far more people access those shops by foot or transit than driving. But have a look at Hamilton for the effect of conversions. People hate driving in Hamilton due to all the one-ways and businesses there started closing soon after the conversion in the 50s. (Note that the decline of downtown Hamilton started long before the industrial economy went to hell). Things have only started to turn around since two major streets were converted back to two-way traffic (James and John).