The legacy of mediums like Usenet isn't jokes but companies, applications, organisations etc. If you grew up during the heyday of Usenet (or BBSes, IRC, some forums, mailing lists) you had a pretty good chance of going on to do something in computing.
Joke can help people come together but they doesn't form the substance of a culture. I guess people from 4chan could go on and be the next generation of marketers or something, but I doubt it.
Not, what I can see, because of 4chan nor because of 4chan culture. By comparison, I know numerous people that started with BBSes, got involved in the demoscene, went on to work for and/or start games companies.
