Hmmm, still can't imagine sauropods with feathers at any stage in life.
Prove me wring science, prove me wrong....
But who knows? If the common ancestor of all dinosaurs had some sort of proto-feather covering, it may be possible that some prosauropods had them too, maybe even the odd sauropod here and there- perhaps not extensively, but maybe like the sparse hair of an elephant or rhino. I know it sounds crazy and unlikely, but consider baurusuchids, a group of land-dwelling Cretaceous crocs; they have a series of pits in their snouts that suggest the presence of complex facial tissues, most likely sensory structures. Crocodiles today have a series of pits too that allow them detect prey in murky water, but this only works when submerged, apparently, so it is possible that land-dwelling baurusuchids developed more complex structures, perhaps analogous to mammalian whiskers. Sounds bizarre but let's remember many of these land crocs developed very similar traits to mammals, including differenciated, cusped teeth, and even perhaps fleshy snouts and noses, as well as an erect posture; some of them, like Pakasuchus, have been said to be cat-like in both shape and presumed lifestyle. If this idea is correct and crocodylomorphs developed whiskers at one point, giant dinosaurs with fuzz may not be so far fetched after all.