Generally, there are only two ways I'm aware of that a qualified student loan doesn't have to be paid back.
1) the borrower is found to be totally disabled and unable to work. (If that status changes later in life, then the loan is un-forgiven and has to be paid back.)
2) The borrower dies. (If there's a co-signer on the loan still living, then the co-signer is liable for the loan.)
