Trump should work with Congress to pass a law allowing Mortgages to be transferrable.
many mortgages are assumable, people just do not realize it.
loans backed by the Federal Housing Administration, U.S. Department of Agriculture and U.S. Department of Veterans Affairs — can qualify as assumable mortgages.
That would solve a lot of the problem.
Interest rates on new mortgages would rise;
and who knows, maybe they would become geographically dependent.
Mortgages are governed by states, not the feds except for fairness, truth in lending, fair housing and FHA and VA mortgages.
Any federal action would apply only to new originations: the terms of existing loans are subject to the whims of policy makers.