If there's anything irreplaceable on them they should be digitised otherwise, personally, I'd bin them. You will then find someone who has convinced themselves that music recorded on cassette sounds better, warmer and more authentic than music recorded on modern digital equipment and wants them.

Vinly records are becoming popular again, by those who know no better, and I hear that people are returning to film cameras; must dust off the old Nikon bodies and the enlarger!