Not only does Toby arrive solo at Kevin's house, but he also isn't wearing a wedding ring. As he tells Randall he brought the sidewalk chalk (not sure what that is about, TBH), he says that he just talked to Jack and "they're on their way." While he could be referring to Kate, he could also be referring to Jack's partner. Randall then tells Toby, "I'm glad you decided to come." Hmm, why wouldn't he come to support his wife? Unless, of course, Kate is no longer alive in the flash-forward.