More straightforward in my mind would be letting people buy their mortgages. In a world of 7% mortgages, a 2.5% mortgage would only trade at ~68% of its value assuming they're both 10 years.
I don't know why I never thought until this moment about buying my mortgage. That seems super advantageous over just paying it off (or buying some other debt at par, since there is zero credit risk on a loan to myself).
