The blanket portion will last longer if you can baste it to another piece of fabric. Minkee would be great because of the feel of it, but you could also use a pre-washed flannel (pre-wash and dry a couple of times to make sure it won't shrink any more). Your grandson would have to decide whether Pooh should get a new tummy or a new back.
You could also baste it to sheer netting (which is how antique quilts are sometimes preserved), but it wouldn't be as sturdy or feel as good.