Canadians had until this point one of the highest ownership ratios in the world, if not the highest, around 70%. Both UK, Europe ( about 50%) and US ( about 65%) are lower. Australia and NZ are right up there too in the high 60's / low 70's.
The two main reasons were cheap land and thus house prices and very low downpayment requirements for first time buyers.
Both of these main factors have been changing - bit by bit - over the last few years as house prices have steadily increased and mortgage rules progressively tightened. This latest announcement is the latest - but possibly not the last - step in increasing mortgage qualification rules. As to the actual effect we shall see but as a rule of thumb you will qualify for less and with less money being available interest rates may go up a hair, especially for non-prime high LTV borrowers and likely investors. Actual impact is TBD though.
==> You can still buy with 5% down and you can still use RRSP money for the downpayment.
Existing landlords rejoice as the pool of renters will increase as more will be unable to get the required mortgage they had in mind.