This point is incredibly important: the estimates should be debated before people get too excited.  

Property Taxes owed= Assessed Value times Tax Rate.  The article is correct if the tax rate does not change, but the tax rate is expected to change.  There is a reason why property tax rates are recalculated annually to six decimal places and have been falling over time (http://vancouver.ca/home-property-development/residential.aspx) while sales taxes are not.  The reason is explained in this video from the City of Vancouver http://vancouver.ca/home-property-development/property-tax.aspx  The same ideas apply in many other Canadian cities: the change in taxes owed depends mostly on the change in assessed value relative to other properties, not the absolute change.