If they go out of business - your mortgage is an asset on their books and will be sold off to another institution who will collect your payments.....You wont notice a thing............until you default....
I was waiting for someone to notice that small aspect of debt.
However, the OP need to default, the new owner of his debt just has to decide to call it in.
In the last "bad one" my mate had a building business, employees, books chocka full or work, excellent cash flow.
Bank called him in, called all his debt in, not because he couldn't pay, BECAUSE HE COULD, and of course that was that, end of business, end of employees, end of all pending work on books, and predictably enough end of marriage and everything else too.
I owe precisely nothing, I will make some purchases on credit card for the protection, but I always clear it in full every month (a revolver) and have no other debt of any kind.
Not because I am a smartass, I just never forgot the lessons from the last one, and never learned to trust anyone else with money, eg banks etc.