That would probably depend on how they are kept as well. My brother's poor abused Shining Force II cart quit on him (at least the battery backup did) after a mere decade), but my own Phantasy Star IV cart, that I've had for just as long, keeps rolling on.
All of my cart-based games save fine, and the disc-based games that haven't been scraped on the sidewalk work fine as well.
I hope to have a nice, functional collection for years to come.