That would be awesome! I don’t ever expect to see Jack again, of course, but they really wasted that actress (she was on Smallville as a main villain/antagonist turned eventual ally), but would be interesting if there was some connection with Jack, Cora, and Jabber too. I wonder if Cora learned something she thought to her advantage about Rumple from Jabber, then she got Wil’s mirror to get back to EF. Jack went with Cora, explaining how Jack ended up in the EF. Cora took Henry Sr. then, and decided to return to WL where she was Queen and Regina couldn’t get to her (this is before her desire to reconcile).
Oh this twisty timeline.
“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