Playlist Shuffle Optimizer

You are given a list of songs, where each song is represented by a unique identifier and has an associated genre. Your task is to implement a function that shuffles the playlist such that no two consecutive songs belong to the same genre.

The function should:

• Accept an array (or list) of song objects. Each song object will have at least two properties: an identifier (e.g., an integer or string) and a genre (e.g., a string).
• Return an array representing the shuffled playlist, ensuring that the genre of any song is not the same as the genre of the song immediately before or after it.
• If it is impossible to arrange the songs in such a way that no two consecutive songs share the same genre, the function should return an empty array or an appropriate indication that no valid shuffling exists.

Example structure for a song object:

{
  "id": "song1",
  "genre": "rock"
}

You can assume that the input contains a mix of genres and that there may be varying counts for each genre. Focus on writing clean, efficient code and include comments where appropriate.

Note: You do not need to worry about multi-threaded environments or persistence; the scope of this exercise is limited to the in-memory reordering of the provided list.