Saran Wrap is a "polymer"...that means nothing. The Glocks are made of a glass-filled (reinforced...not unlike the fiberglass in a boat hull) polymer (plastic). If Glock uses a polymer compound that is UV stable that resists heat degredation...which I'm sure they do, then they should last just about forever.
Besides...it's not like they can get any uglier.
Besides...it's not like they can get any uglier.