Originally, Kojima wanted to open Metal Gear Solid V with the song ‘Diamond Dogs’ by David Bowie. Diamond Dogs is, of course, also the name of the new mercenary unit formed by Miller and Snake, after the destruction of Mother Base and MSF in Ground Zeroes.
However, Kojima’s team was against this idea. Maybe it didn’t fit the tone of the game well enough.
But who knows, you might be able to find a cassette tape with the song for your Walkman in The Phantom Pain.