Walmart Stores within a 50 mile radius of our home have had no fabric dept. for several years. I did visit one store, my favorite, about 75 minutes away that has installed what seems to be a "just for quilters" section. The display was very attractive and contained pre-cut fat quarters, fat quarter co-ordinated and seasonal theme bundles, some jelly rolls and stacks of squares and also larger cuts. The store buyer seemed to have stocked contemporary quilt colors and fabric designs. I am NOT an expert on fabric but most of the goods reminded me of stock from five and dime stores. Rough feel, coarse texture and unnaturally stiff. I did not (but I wish I had, to wash and try) buy even a fat quarter. It may or may not be good. On the other hand feedsacks weren't made of what we would call a quality fabric but many things made from them have survived in good condition. Some real testing would help.
I am not down on Walmart fabric, per se. Our closest store had a nice sewing department previously with various qualities of yard goods and very, very cute novelties, Mary Englebreit, panels, etc. which I happily purchased. They carried clothing patterns, household and fashion fabrics, vinyl, etc. We were sorry when it disappeared from the store.