How far back is too far back for a 50-year-old? And how far back do you have to go before a 50-year old considers a song "classic/gold/legend/oldie?" Taylor Swift's "Love Song?" Jamie O'Neal's "There is No Arizona?" Merle Haggard's "Working Man Blues?"
That's a good question, and it varies by individual. But radio doesn't program to individuals, unless we're talking about a subscription-based online station. Most of the responders here who like this playlist do that kind of radio, and it's a very different ballgame.
Generally we're seeing that 15 years ago is the cut-off for a currents based country station. If it's older than 1997, it's too old. Most currents based stations, the ones that play Brantley Gilbert, are 50% currents. But those stations are appealing to audiences that are 60% female under 40.
On the other end of the spectrum, the absolute bottom for a 50 year old is 1970. However, it's not out of the question to throw in a 60s classic by a major artist once every 4 hours, like Mama Tried or I Walk The Line for men, and a Patsy Cline for women. That's the "wow" song.
The real sweet spot isn't age, but gender. Typically, a male listener around 50 has formed an opinion about country, and it's built around the music in the 80s. That means they will be violently opposed to Colt Ford, Rascal Flatts, and Taylor Swift. He'll put up with it to make the female in his world happy. Females are more open to current female artists like Taylor, Carrie, and Miranda. Anyone who's associated with those women are OK too. Women tend to like Cash but not Haggard or Jones. They prefer Loretta and Tammy. Men absolutely don't get K.T. Oslin. Women don't get Waylon. Everybody likes Willie. Or at least say they do. The easiest way to empty a room is play Achy Breaky Heart.