This is a great point! However I'm not sure about your proposed solution. You'd have to give up a fair bit of the difference in interest rate to incent the ban

This is a great point! However I'm not sure about your proposed solution. You'd have to give up a fair bit of the difference in interest rate to incent the banks to agree to this. There would likely be a selection bias that most of the people who would take advantage of it were going to sell anyway, and now the bank is stuck carrying a sub-market-rate loan they otherwise would have gotten out of.