I honestly can't see any network show doing a stable, romantic OT3 relationship in canon

Yeah, I don't think I necessarily need it to be romantic, you know? I would be happy if they could find some way to resolve it that reinforced how important they all are to each other, with or without smooches. (There's always fanfic for smooches.)

But we probably won't get that either, because apparently everyone has to be paired off, two by two. ;-P