<i>Anything that is 20 years old has either long ago become ubiquitous...</i><p>That's kinda the point of the modern IP playbook: to get <i>everyone</i> to pay license fees for your technology.<p>There are plenty of patents that only make money in the final years of their term. For example, RSA was patented in 1983 but didn't come into widespread use until ~1995 and the patent expired in 2000; if the patent lasted 8 years we can assume that they would have made no money at all. (Of course, since the inventors of RSA were academics it's likely that the patent value provided no incentive towards the invention of RSA.) LZW is a similar story.