Where will your links go?

Here is question for you. Where will your links go? I have found that approx 50% of the links I created in 2005 are gone. OK geocities was one important. Still, one SEO expert says that 80% of your links will be gone in less than half a year. Folks, this is max scary. All that effort down the drain is not my idea of how to make my place in the search engines.