I have few clothes, so half of one closet has 3 homebuilt shelves. I store currently unused quilts on those shelves. They get refolded at least once every three months that way. I know a lot of people make pillowcases to store unused quilts in, but I struggle so hard to get them in that I decided not to bother. I store my sewing machine rolling cart underneath.
I don't have the space to keep 'unused' quilts and I'm not saving stuff for 'future generations' since fabric ages into unsuitability either by taste or deterioration. I am now giving quilts that I no longer love as gifts to those who appreciate such things. This is not to say that YOU shouldn't keep older quilts to pass on to younger generation. I'm just saying, don't keep what you don't love. Most of us have way too much clutter.