Jokes aside, I figure we have another 0.75-1.25% of this rates cycle still to run. I think you may be surprised at how people still manage to get by.
The effect of interest rates decreases with the length of ownership.
People who have owned for 25+ years have likely paid off the mortgage, so interest rates are irrelevant.
People who have owned for 12 years have likely paid off 1/3 of the mortgage, and their wages have doubled since they bought the place. So someone who owns a 600k property now might have bought the place 12 years ago for 300k when their salary was 60k. Now, the mortgage is 200k, and their salary is 120k. An increase of 1.5% in interest rates would be 3k. What's 3k extra payments to a person on 120k?
People who have recently bought are going to be stretched. They don't have much equity so they can't just sell, as the bank will come after if it's not enough. What's more likely is that they'll try to get by and cut their expenses to the bone. Unemployment obviously increases the risk of default, which is why 2007, for example, saw more repossessions in Sydney. But of course, a recession likely means rates will go down, helping those who still have jobs and mortgages. The unemployed will be vulnerable, but they always are whether rates are low or high.
The recent owners are the likeliest to rent out their rooms, but only because they need to. Even so, human behaviour being what it is, once you move into 'your' home, renting out rooms and sharing again will not be the first response to financial strife. More likely, they'll cut expenses, and most households have a lot of 'fat' to cut in their budgets.