So imagine Korra doesn’t get her bending back at the end of the season. Imagine Aang does show up at the cliff, and Korra’s thrilled to see him, but she quickly senses that something isn’t right. He isn’t smiling. She’s not actually in the Spirit World. This isn’t the way it’s supposed to be.
They sit and talk for a while. He tells her that him coming to visit her like this is going to be a one-time thing. He’s trying to stay impassive, but he’s clearly sad. Korra asks him what’s wrong, what’s going to happen to her. He says that isn’t for him to decide. Slowly, Korra starts realizing that he isn’t going to be able to solve this problem for her. She eventually asks him flat-out what’s going to happen to her bending. Aang tells her she won’t be able to get it back.
Korra already felt despair over this idea, but hearing it from Aang himself shocks her. He goes on to say that while it isn’t a punishment for her actions, it is a consequence. It’s true that the spiritual connections don’t come easy to her, but it was her job to at least meet them halfway. She failed to do so. She spent all of her time throwing herself headfirst into dangerous situations, believing she could fight her way through life before learning about balance, the human experience, and acceptance. Because of her upbringing in the OWL compound, she relied on her fighting prowess and treated her life as a test run. She always assumed that the spiritual connection would happen at an abstract time in the future instead of striving to meet it every day. It wasn’t completely her fault, but it happened, and nothing can change that.
Korra is only half-listening, still stunned about her bending. Aang stands up. Korra finally snaps out of her shock and asks him to wait, to help her figure out a way to reverse what Amon has done to her. Aang tells her that everyone has an obstacle to overcome in life. Some are born with it, some encounter it later. While she has friends and family to support her, this is her journey. He apologizes and says that he has to go. The tears finally well up again as Korra asks him how she’s supposed to be the Avatar with control over only one element. Aang, as he starts to fade, says that it’s something she’ll have to learn to accept.
Essentially telling her in more polite terms: “You’re the Avatar. You gotta deal with it.”