I don't see the point of the indicator at all.

It would only apply to playlists and tunes (I'm not aware of anwhere outside of the playlist menu where press and hold applies) and it would apply to all playlists and all tunes.

I assume what you want it for is to alert the user to the fact that press and hold is available. But it they don't know that press and hold is available (and what it does) within the playlist menu then changing the colour of the menu (or whatever) is not going to suddenly impart this knowledge to them.

If the press and hold feature only applied to some playlists and some tunes then it would make sense. As it applies to all of them it doesn't.