It seems unlikely that we will ever produce materials that disobey the laws of thermodynamics.i.e. clothing made out of a material that makes bullets bounce off back where they came from without imparting any energy
People have this odd idea that anything they can imagine will someday be achievable by technology, but technology isn't magic, and scientific advances don't make new things possible - quite the opposite, science is the process of whittling down all of the imaginable things into the tiny subset of actually achievable things. Science doesn't make more things possible, it just makes it easier to sort the possible from the impossible.
And "clothing made out of a material that makes bullets bounce off back where they came from without imparting any energy" lies squarely in the 'impossible' camp.
Yeah, some time ago I got to thinking of how a sci-fi return-bullet-to-sender approach would work--and it doesn't seem possible. To actually return the bullet to the sender you need to send it back at the same angle and with the same ballistics.
If you have a good enough track on the bullet you could make a handwavium gravity generator that dropped a gravity field in it's path that flung it back. However, now it's going backwards and it's not symmetric. The reflected bullet won't go as far--against a nearby shooter it wouldn't matter, against a sniper it would.
Note that the departure angle is not a reflection--you would need a cornercube reflector, not a plain mirror. And cornercube reflectors only work within the reflector, they have edges where reflection doesn't happen. In normal real-world use they're always reflecting photons so these edges don't really matter, but a bullet shield either has to be bigger than the target or consist of many reflectors that have edges in between. (Common real world examples are those highway marker signs that you can see from far away when your headlights light them up.)
Disagree--weapons can become obsolete because they are countered too well. We don't have any really good examples, but consider the WWII anti-tank rockets. Even if you don't have the modern stuff you wouldn't use the old stuff because it's not going to punch through the armor. Such weapons still exist but only for use against soft-skinned targets.Weapons don't become obsolete because they are less deadly; They become obsolete because they're replaced by weapons that are equally deadly, but faster, easier, or and/or cheaper to use.