Toby's decision to dump his meds was directly linked to his desire to be a dad — so what if that actually does come true? It's definitely still a theory in progress, but since we know Toby is linked to the "her" mystery (and that This Is Us likes to subvert expectations), is it possible that "her" is not Kate or Beth or Rebecca, but a daughter of Kate and Toby? If this is the case, then something still goes horribly wrong along the way, given how sad Toby is in the flash-forward. There's not much evidence one way or another on this theory yet, but it's a theory to keep an eye on for sure.