I doubt this will happen.


First, plastic degrades. No one will buy a lens that eventually breaks down, due to exposure to UV.


Second, it's got a problem with expansion and contraction that is worse than the glass.


Third, it will scratch more easily, making handling it in day-to-day environments problematic.


Fourth, depending on the polymer, it will slowly yellow on exposure to UV, changing the color of the image right out of the camera.


Fifth, many polymers are "hazed" by exposure to certain solvents, chemicals, etc. This increases its chance of being damaged.