Although, just because the prime rate goes up, your fixed interest payments wouldn't increase. So most will be OK. It's the ARM guys that will feel the pain.
OP was talking about Canadian household debt, and as I understand it, Canadians don't have access to 30-year fixed mortages like folks in the US do. It sounds like they get a fixed rate for 5 years, at which point they have to get another 5-year loan at the new rates. Maybe a Canadian 'stache can chime in?
Yep, some fixed rates with longer terms are available, (7 and 10 year are not uncommon) but 5 year rates, (renew every 5 years) with both fixed and variable rates being equally popular is normal.
Canadian mortgages are held (mostly) by the bank paper -- issued GIC's and the like, which the banks also sell on 5 year terms, which is partly why the 5 year mortage rates are a "sweet spot" for both sides. (Banks make profit on the spread between mortgage rates and GICs, and often hold the mortgages themselves without selling them on).
Anyway, the 5 year mortgage renewals make life quite exciting, if you no longer have the same income as orginally. Usually you started with at least 10% down, and after paying the mortgage for 5 years, you enough equity to renew.... but you need to requality for the debt service ratios of 32% (home) and 38-40% (total).
It also is quite scary as interest is very low right now, so each 1% increase in bank rate (from 2% to 3%) means that your monthly payments jump by 12%.... or by $250/mo on a 500k mortgage....