I started a thread on Sound archives decaying a while back, after seeing a piece in New Scientist. Mag tapes may become unusable. I'm archiving all my stuff on CDs. It will take me years (at the rate I'm going), but before the new medium becomes too badly degraded, I hope there'll be a newer and more reliable technology to transfer the archie on to.

BTW, you can get turntables to play 78s, ranging from the basic to the fantastical: see that link above.

Steve