There are a ton of 8mb cards still around and working fine. I've never had a CF card die since I started using them 13 years ago in my Nikon CP-990, which is also still working great.
Cards are more likely to fail from other causes than wearing out. For the most part, users do not come near to wearing them out, but certainly some users will wear them out.
I would not worry about the life, you will want a larger or a faster card long before yours dies. I upgraded to a 85mb card in 2000 at a cost of $200. It was only a couple of years before I started buying 2GB cards, then 4, 8, 16, 32, and now I buy 64 GB cards. I usually sell the old ones with a camera, so I think most of mine are 16GB or larger. I do keep a few smaller ones because some of my old cameras like my CP 990 max out at 2GB.