I wouldn't say it's outdated exactly. It is no longer officially used and there's been some token admonition to stop using the term, instead favoring nonbeliever or non-JW. However, I only think I heard it officially advised against once which seems entirely insufficient given the decades of use the term got.
Because I've seen no decline in the frequency with which the term worldly is used, I would be more inclined to categorize this as a new insider doctrine. It's yet another in a long line of things that are hidden from potential recruits and the world at large in order to protect their image, but once in long enough it will be learned.