I wrote this on the other thread of the spoiler and i will post it here again
I saw someone posting a interesting theory about this online, the person was saying that this is the music name, that probably was used in 319 when Neal send the warning to Hook and that Mark keeps re- using old songs from past seasons, since no more soundtracks from the show were released, so this is just the song name, because Mark would not change the song title , just because will be used in another season, so the tune is the same, the name has to keep being the same. So can simply means this is a song name and not that Neal is not back, Mark is just using that song composed for 319.
I think this is actually a interesting theory and probably the thing that will happen, bc lets be real, why would they want to keep a secret of Neal cameo in epi 100 , when so many other characters are coming back? In fact revealing that fact could make them gain viewers, so if this was true and Neal would appear even if in one scene, they would only gain, so no reason to keep it a surprise during so many time.
In the end this would accomplish several results, Bait for ratings and using MRJ name and future media attention on him to get OUAt name out there, and get free publicity.
"I offended you with my opinion? Ha, you should hear the ones I keep to myself".