In regards to this concern.
1) If the fail safe does in fact kill everyone, then obviously Belle is going with Rumple. It makes absolutely no sense for him to ask her to stay behind. In an TV guide interview, which you mention, Bobby even says that Rumple’s sole concern is getting Belle back. He is not about to get her back and then leave her again. It makes NO sense.
2) Also, if SB is going to be destroyed or abandoned and never seen again, they aren’t leaving EdR behind. She’s a full cast member and to separate her from everyone, especially if we’re never coming back to SB makes NO sense.
3) Tumblr and LJ are not reliable sources of information. We’ve seen EdR at the docks with the rest of the crew. I take this to mean that she is Belle again and she’s not about to stay behind while everyone else goes.