I thought about this while randomly looking for info on what happened to Moira Quirk, the referee/scorekeeper on Nickelodeon GUTS. She went on to be a fairly prolific voice actress and award-winning audiobook narrator.
That's still showbiz-related, though, so not really too big of a switch. But are there other examples like, say, Geoff Edwards (who became a prolific travel writer/blogger after game shows dried up) of personalities who went into something nearly completely unrelated?