Well, there’s no air, and therefore no wind on the moon. There’s really not a lot that could wipe out the footprints. They’ll be there a long time.
What will happen, eventually, however, is meteorites striking the moon. Really big ones might make the ground shake where the footprints are and cause the fine dust on the moon’s surface to fill in the footprints. There’s another kind of meteorite on the moon – small ones. Some of them are just micro in size. So over time the moon’s surface gets pulverized.
There is still another scenario caused by really big impacts. Since there’s no air on the moon, debris from those impacts goes up and gradually falls down over the surface of the moon.
Eventually, you’ll just wind up with a bunch of moon dust.