Using a laser stylus from a company like this, the records will be readable for centuries, if not millennia.
Laser Advantage Because there is no contact, the laser reproduces
without any distortion. The laser picks up all of the audio signals in
the groove, lower signal through higher as it is. This results in
laser sound quality that is quite similar to the original sound in the
recording's master tape. Most of people never get to hear the master
tapes, but with the Laser Turntable, you get comparable quality, as
acknowledged by Professional Sound Recording Engineers in Japan.
No Contact and No Wear The same audio information has been engraved on
the groove wall from the top through the bottom. A stylus reads audio
information close to the bottom. The laser reads audio information
close to the top. Namely the laser reads audio information which never
been read by a stylus, without any contact and without any
digitization or audio compression.
Since one inch (2.5 cm) of grove record approximately one second of audio, degradation over millimeter sections will result in only millisecond aberrations in the sound. It is not like a DVD, where very small areas of local damage can cause severe glitches in audio.
Since the analog signal on a record track maps the frequency exactly, with the eventual degradation of the PVC, it will be the high end frequencies that are lost first. The lower frequencies will remain intact. That is, unlike digital, there is always information that can be retrieved from all sections of the grove, even if it is damaged, until the track is totally destroyed. With digital, ALL information is lost in a sector if ANY information is lost, on most players.