50 years plus was obviously a joke, but "old" can definitely be attributed to "not new". Also headlined can be defined by anyone their giving attention to in a push and featuring on TV, so it doesn't necessarily have to be main event, either.
Best example can be The MEM. Kurt Angle, Scott Steiner, Kevin Nash, Sting, Taz. They "headlined" that show for the greater period of 9 months, and the majority of these people aside from Scott Steiner are still in the main event and still being pushed in the top spots. Also Ric Flair (by being placed with AJ, and the amount of TV time he's had with AJ, over 60), and of course but not least, HULK HOGAN (over 60). I can only count one guy that's in the same shoes as them that isn't an old name, and that's AJ Styles. Desmonde Wolfe can be arguably placed there, but he's only had a few matches with Angle and is already in the mid-card (of course this is natural, so i'm not saying it's TNA's fault or a bad thing, either). Of all those old names, the only two that I think can actually contribute athletically speaking is Kurt Angle and Sting. The rest have no right being in a ring at the level they are.
However in WWE you have Randy Orton, Kofi Kingston, Sheamus, the Miz, Drew McIntyre, John Morrisson, CM Punk and probably a few other guys I'm forgetting atm. For old names they've got Triple H, Shawn Michaels (These two are debatable as well because they can both contribute a hell of a lot more than even some of the young guys), and VERY arguably Chris Jericho (he has been on an upswing for the last 10 years bar his hiatus, without a sign of slowing down either), and Taker. Names like Kane and Big Show are irrelevant because they have NEVER been headliners (Kane is the only arguable one, but aside from his one reign and his WM match with Taker, he's gone nowhere). Bret Hart cannot be even considered because he can't even wrestle due to physical restrictions.
WWE doesn't have any wrinkly old guys wrestling in main event matches, the last one they had was Ric Flair and now he's adding to the pile in TNA. All the "wrinklies" in TNA can't do half the job that the veterans in WWE can do in putting a guy over, nor can they work a match even a fraction the quality of those guys, aside from Angle and Sting, and of the two it's a huge debate on Angle because we all know what happens when that guy feels the pressure and burns out (which was happening a little over a year ago when he was losing weight and bragging about it backstage to purposely keep his spot in the top, although all of that positioning was completely unnecessary because he's Kurt Angle; his level of competition is unmatched by ANYBODY, and he will be able to go until he "breaks his freakin' neck" again.
The way I see it, and it is only MY OPINION, is that TNA is housing all the old, useless, washed up hacks that nobody cares about anymore, and barely making a dent in putting over the young guys the way they should be (Sorry, the definition of Kevin Nash putting anyone over is a joke, it takes two to tango and when you have guys like Eric Young that can't get themselves over, it makes it hard for anyone to GET them over. And IN MY OPINION Eric young is not over).
This is just a debate, you don't have to go and flood your replies with swears and derogatory remarks. People have opinions, some people might think TNA is favoring washed up hacks over fresh talent, and some may argue WWE doesn't use their young talent correctly, but at the end of the day it is their opinions and you can't get angry at someone for voicing them. So just calm down and let others speak their own mind. I'm in no way implying any offense against you, it's just that you don't need to get angry because 3 different people disagree with you for many different reasons, it's their right to do so if they wish.