You're right in that there is a segment of homeowners coming up to refinance who is asset rich, because the price of their home has increased, but they don't have the money to pay that higher mortgage rate. Refinancing and temporary payment relief are some policy levers, but it's hard, in the short term, to really fix it.
When you look at the debt service ratio, it's going to be a systemic problem across Canada. When you look at bigger centres, such as Toronto and Vancouver, that's definitely a concern.
As far as a policy lever is concerned, it's not completely obvious what it would be, besides some temporary payment relief.