This Is Us season 4 ended with Kevin (Justin Hartley) and Randall (Sterling K. Brown) not speaking with each other; however, it won't be too long before the brothers come to their senses and make up. With NBC's family drama ing the midpoint of its story, fans are starting to talk about the endgame for the Pearsons. However, things don't look like it'll be a walk in the park for the family. Aside from Rebecca's (Mandy Moore) deteriorating mental state, there's also a full-blown conflict between the brothers.
After devoting three full seasons to Jack's (Milo Ventimiglia) story, leading up to his tragic death while the Big Three were in their teens, This Is Us has shifted its focus to Rebecca. This is Us season 3 teased what lies ahead for the Pearson matriarch, and now viewers have a clearer idea of her path down the line with Rebecca's degenerative condition confirmed. This is obviously a difficult time for the family, so it doesn't help that Kevin and Randall have different opinions on how to tackle the matter. While Number One wants to abide by their mother's initial decision to not go to clinical trial, Number Three continues to force the matter - even manipulating Rebecca into changing her mind.
The whole thing blew up in the This Is Us season 4 finale, "Strangers Part 2". Upon learning what Randall did, This Is Us season 3 finale. However, contrary to the general assumption, their rift won't last long, as was implied by a major flashforward scene.
When This Is Us first revealed Rebecca in her death bed back in the season 3 finale, Randall, Beth (Susan Kelechi Watson), and grown-up Tess came to Kevin's house. While Number One wasn't around, his son was - roaming around the house and greeting his visiting family. Randall then called to him and asked where his father was. This is proof that Randall and Kevin's reconciliation comes sooner rather than later. The brothers’ fight takes place before the twins' are born, and considering that Randall and his nephew seem to have an idea of who each other is, it's safe to say that this wasn't their first encounter. Perhaps both eventually come around and decide to patch things up for the sake of their mother in the coming months. In any case, this indicates that Kevin and Randall make up before the family gathers for Rebecca’s death.
Storytelling-wise, it also doesn't make sense for This Is Us to keep Kevin and Randall separate for the next two seasons, assuming the show's flashforward fully pans out at the end of season 6. Despite some harrowing events peppered throughout its run, the series always makes sure that the light-hearted moments outweigh the bad ones - that's what makes it so cathartic. That would be difficult to accomplish with the brothers having limited-to-no interaction. This makes it possible that they'll eventually reunite quicker than most people think.