Board Thread:Spoilers!/@comment-26159109-20170115054549/@comment-24674051-20170117173414

Back to the topical question.

Of the characters on the show, I think that it would be difficult at this point to see the show without Emma or Regina. Not impossible, just difficult. Every other character can be replaced.

Personally, from what I read, it does not appear that Jen would leave the show of her own accord. BUT, just for arguments sake, let's suppose that she did. The only reasonable way to write her character out of the show would be to have her killed. The show started centered around Emma, and she has been much of the driving force for each season:

Season 1 she is led to SB and breaks the curse

Season 2 she journeys to the EF, leads Rumple to find Bae, and works with Regina to save SB

Season 3 she is the leader of the trip to save Henry, and is the one of the main focal points during the Oz arc, including the season finale.

Season 4 - Emma was the "chosen" sister for Ingrid, and was the target of Rumple in the Queens of Darkness

Season 5 - Dark Swan and leading the trip to the UW.

Season 6 - Saviorology and the conflict with Gideon.

So, to take this character that has been central to the entire show and just "Move her to the back burner" would seem like a weak move, and hard to explain. Emma as a character would not just go back to being a Sheriff and watching the action from the sidelines. And moving Emma to the back leaves very little reason to keep ANY of the other characters.

Killing her, on the other hand, leaves the door open to retain the show's other core, and spin at least a mini arc around resolving and avenging her death, which would also allow possible new central characters to emerge and develop. It keeps Emma's character central for at least the short period of transition.