Thanks for starting this thread--it's been an interesting read.
As far as quilts lasting--that depends on how they are used. The pristine examples we have from ages past were not used everyday and not allowed to lay in the sun. Right now I have a couple of 1990 era calico type 9P and snowball quilts that are deteriorating fast. Why--because my kids used them on their beds and they were thrown in the washing machine regularly. The quilts served the purpose for what they were made for.
Thanks SSK :-)