"How long will my CDs last" is like asking "how long will I live." There are a bunch of variables involved (in both, actually).
I was just preparing a blog post on the topic of bit rot, which was inspired after I discovered several of my oldest CD-R discs recently stopped working. Many early CD-R disks are susceptable to "flaking" -- the gold layer will just start peeling off, and when that happens it's all over. Another type of bit rot is CD Bronzing, which affected several labels of the late 80s and early 90s.
As a general rule, store bought (or "pressed") CDs will last longer than burned discs. If you haven't lost any CDs yet, well, lucky you. As someone who's seen it first hand, I can tell you it sucks after thinking that CDs lasted forever.