It’s mind bendy awesome. Obviously they couldn’t copy the concept exactly because copyright, but they could still take the concept and make it their own.
Like, if this is essentially what Zelena plans to do to Regina, burn her “thread” back completely to erase her existence, then maybe she succeeds, (hence the BTS pics from the finale) and then they manage to turn the same process around and use it on Zelena, and burn her thread back to at least before she left Oz to shack up in Regina’s castle, which was the point in her history when she became a threat to them, so they need to undo everything back to that point in order to defeat her.
I guess that could essentially leave them all back where they were at the start of 312, but still potentially with the memories of everything that happened from 312 on if they keep that aspect of the baelfire concept. So Regina would know that her psycho sister is gonna hijack her protection spell, so she’s gotta get to the castle first to set a trap for her. And Neal and Belle know about the Vault, but they also know the consequences of using the Key, so it goes back to Belle’s comments that they’ll find another way to bring Rumple back. And Emma and Henry are back in NYC, but they now know that their family and everyone is back in FTL, and they know that Walsh is the MonkeyWizard, and Emma can ask him to help them reunite with everyone, kill Zelena, and break his Monkey curse.
(Stream of consciousness crackpot theorising at 3am FTW. 😛 )