The way that Jennifer talks about this show is completely different. She used to really praise the writing; now she doesn’t. Now she says, she loves Emma’s character and she is glad she did Ouat because it got her into directing. That is what she says now. Everything in that interview was she wants to finish off Emma as a character because she really loves that character, but she can’t do it forever, she can’t be on Ouat forever, she wants to direct, do other projects, aka implying she is ready to move on.
To suggest that Jennifer wants to stay is a complete vocalization of your thoughts when she specifically stated that she can’t do this forever, that she wants to direct which is, as i said, implying she wants to move on.
Also, while the many characters have multiply connections, some could be cut out and the plot continue on. I think Emma is the center of this show and the normal person and to cut her out and just continue on could only happen with a complete change of how the show works and how characters interact. I think that Regina has become the second center and is connected to Snow, Rumpel, Zelena, Emma, and Henry in ways where her removal would change everything about how the characters interact. The removal of Snow and Charming, while a great loss would just mean they wouldn’t be invited on the quests and their story would be finished off. The same with Rumpel, his story would be finished and he wouldn’t be there to ask for magical help.