On rewatching, I noticed–Felix has his shadow. You can see it as the Lost Ones walk past Hook while he is hiding Bae in the deck below. All the boys walk and their shadows are reflected on the door. This scene is immediately following Felix telling Hook about the ripping, so if there were ever a time they wanted to make sure you’d notice Felix doesn’t have one–that would have been it.
I agree then–that something special happens with a ripped shadow, and that most likely, it will happen to one of our main character. I’d bet Rumple too.
“If I had a world of my own, everything would be nonsense. Nothing would be what it is, because everything would be what it isn't. And contrary wise, what is, it wouldn't be. And what it wouldn't be, it would. You see?” -- Lewis Carroll, Alice's Adventures in Wonderland & Through the Looking-Glass