I'm talking about government debt, not private. Though, a chain reaction , if it is to happen, will reach pretty much all and everything including private mortgages.

If you have a fixed rate one, you may well read the fine script better. Quite a few banks put a no reservations callback clause in the loan agreement.

If an individual gets his mortgage called back, for an average Joe the only way to get through that would be to get another loan, and at a higher rate.