I don’t see the connection between Robin’s death and the audience knowing the name of the baby. It’s as if back in season 3 MRJ would have said that the audience would know what is the name of Snow and Charming’s baby.
Robin can die, then Zelena names the baby.
That video from twitch took place after all the filming. And when Sean mentioned he would love to see some of the jungle book characters in the show (since the new movie will be released), he said he would love to see his child watch him work with Baloo the bear. That sounds like a clue that he will continue appearing in s6.
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