The reason $5 bills are still being used frequently is because it's the same $5 bills juggling around in circulation for many years. I bet, once the existing $5 bills are due to be replaced, they'll probably be replaced with $10 bills since it appears they may be rebounding in circulation. $10 bills were not being used broadly for 30+ years, and it may have been due to the likeness of a certain man who caused controversy (possibly exposed in the late 1980s or very early 1990s), and his dark past was further exposed in recent years which may have prompted the Bank of Canada to recall all $10s with that man on it, though the Canada 150 version - which does have his likeness - still exists in some capacity but are gradually disappearing. This may explain the Bank of Canada's decision to keep Laurier on the $5, and I wouldn't be shocked if King and Borden will continue to appear on the vertical $50 and $100 bills - whenever that may be (I'll probably be retired from my job by the time either gets released).
$10 is the new $5
I agree on what you said about the $5 bill being replaced by the $10 bill. A main factor of that is because of inflation causing people to use higher denominations such as the $10, $20 or even the $50.
The $5 bill is still used frequently in my experience as I see people using the bill for purchases under $5 and sometimes the cashier would give out 10-15 dollars back in change in fives instead of a ten and a five. Also worth mentioning the $5 are frequently worn out.
I still see the Canada 150 and the Macdonald bills in circulation but not as frequently. I do remember the BoC was going to take all Macdonald bills out of circulation but I still do see some Macdonald bills in my change or withdrawing some cash. I remember 3 years ago there were a lot of Macdonald and 150 bills circulating in my area but now it’s been reduced due to wear and tear as they are being sent to the Bank of Canada for destruction.
I like Laurier being on the $5 bill and there are many ways they can honour important Canadians. It depends if the Bank of Canada will replace the face of the $50 and $100 with Laurier and Macdonald which heard from a article I was reading