I find they last the obligatory 2-3 years before they begin to wane.
Most of mine have lasted 2-3 years but barely made it a year before starting to wane in one way or another. The most common one, and sad to see even on expensive ones, is the surface starting to crazy crack and flake even in areas with minimal contact and even on ones which "aren't" just cheap plastic or pleather finishes which probably points to an inferior material as the leather seats in my truck have seen a ton of abuse and still hold up fine.