Before his rapid decline, Hedberg was arguably the best club comic of the last decade—an achievement that sounds, in our era of cross-promotion, something like "the best backup shortstop on my mom's slow-pitch softball team." But that was his real ambition. In interviews and in his act, he always insisted that stand-up was a self-sufficient art—he joked that the industry's drive to convert comics into actors and talk-show hosts was like saying to a chef: "Alright you're a cook. Can you farm?" Even at the height of his success he toured relentlessly, headlining four nights a week at smallish clubs and college campuses. He died, in fact, in a hotel room between shows.
Hedberg was an awful candidate for the next Seinfeld, not because he wasn't funny, but because his humor was so deeply rooted in stand-up. It was his native language; anything else would have been a clumsy adaptation. We're lucky, in a way, that he never crossed over. There's something sacred about the untranslatable (the Italians have a proverb: traduttore, traditore—"translator, traitor").
The "next Seinfeld" position is currently vacant, though there have been murmurs about, for instance, Arrested Development, and even about the recently canceled and deeply un-Seinfeldian series Committed. Success on the scale of Seinfeld is essentially beyond prediction, and it has nothing to do with stand-up comedy. Maybe Hedberg's death will mark the official end of the search.