if they are still in good shape---i don't believe age has anything to do with it- i work with someone who brought me a tumbling block quilt top her great-great grandmother made in 1883---she wanted it machine quilted- just to keep it together---there were a couple small places which were frayed a little bit- but the fabric although thin- was in good shape=
i carefully fixed the small frayed places- bought a nice backing- cotton batting and quilted it- it came out so great! she is thrilled- to the point of deciding i didn't charge enough and it paying me more than i asked- and has told me there will be a couple more.
age does not matter- the shape it's in determines how well it will hold up to finishing-