Nice try, but the Pregnancy for Regina seems out of the question. She cursed herself to not bear a child against Cora in season 4. Remember?
I do — and if that wasn’t a set up for a future narrative arc that would reverse the effects of this decision, I don’t know what is. Not to mention that this wouldn’t be the first time OUAT retconned something it previously presented as axiomatic. There’s always a loophole, and all that.
Anyway, I think it’s definitely a plot line they might pursue at some point, if the show runs that long. But I can also see how they wouldn’t go there right now. There’s a baby boom on the show as it is — maybe there’s an allotted baby quota they can’t exceed?