In some ways, it's a pointless discussion. Songs that are known as 'classics' generally have been made so by sweetheart royalty deals signed decades ago which guarantees they appear on commercial radio playlists. They form a default brick wall of songs which get played to death and, in the cracks of that wall at specific timeslots, only then does new music get played which, again, are all subject to the deals signed by majors with radio stations to get them on playlists. Only on small community radio stations do playlists not apply in a blanket sense and some of the bigger ones do use them. It means guaranteed airplay according to the whims of the record companies.
The point; what are 'classic' songs has been largely manufactured. Play something often enough and it'll start to be regarded as a 'classic', regardless of artistic merit. Not bagging the system, it is what it is.