Well I wouldn't give up porn for real estate right now. That's for damn sure.
Porn can teach you very agressive marketing skills which you can diversify and apply to mainstream site ideas (from t-shirts, to ebay, blogs, stores, etc) at any time. But if you mean that mainstream sales payout rates are higher than adult you're nuts, when it comes to making more online as a 'webmaster'.
Fulltime salaries at adult companies and mainstream companies at about the same size are pretty similarly sized firms. It's more of a choice of speciality question than in/out of porn question. To a server admin for an adult firm vs. a mainstream firm, he may careless or even be more challenged in adult - but also have more fun
