If Neal in that moment hadn’t left his father and ensured that someone went to get Emma then Zelena would have them all trapped in SB, taken the baby and changed time.
Yep. Hook would still be off sailing whatever realm. Emma would be engaged to a Monkey. Zelena would be the midwife in the delivery room ready to snatch the Snowflake no worries, because they never found out who she was. They’d all have just wandered around without their memories with no way to break the Curse because Henry wasn’t in town and no one could go get him (Snow probably could have, as Curse caster, but she didn’t remember so didn’t know). In that minute or so of screentime, Neal was the hero who saved them all. If they defeat Zelena, that’s possible because of events Neal set in motion when he had the strength to send that note.