I think fabric can be kept indefinitely. I had a friend whose mother in law died several years ago, in her 80's. She had worked at a department store chain like Kresges that went out of business and had stashed 3 yards each of many different fabrics from that store. My friend shared some of it with me and I made things like jackets, vests. skirts, etc out of it. I preshrunk all the fabric and the clothes have been fine.