The Apollo astronauts’ footprints will stay on the moon for 100 million years
Because there is no atmosphere on the moon, and hence no erosion, the Apollo astronauts’ footprints, roverprints and spaceship prints will stay preserved on the moon for at least the next 10 to 100 million years.
They won’t stay on there forever, though. The Moon is exposed to bombardment by meteorites that could easily wipe out a footprint on the moon. The Moon is also exposed to solar wind and over time this acts almost like weather on Earth to scour surfaces on the moon, but the process is very, very slow.