The original question had to be edited down. Though the ending of the story might not present it to be such, I think that Rakesh is a devoted son. He is devoted to his parents. He does everything that is asked of him. He does well in school, achieves and succeeds in a profession that brings his parents pride and joy, marries a woman of their choosing, comes back to India when they ask, and tends to his father when he is a weakened state. He is devoted in that he is able to put his aside his own wishes for their betterment and their word. The bond that he carries as their son does not dissipate as he gets older. In other words, he remains their son, even taking priority over as husband or father.
In this light, Rakesh would have to be seen as a devoted son. There is little more he can do. The ending of the story where he denies his father his wants is only done because of health concerns. Rakesh is simply using his own knowledge, gained at the wishes of his parents, to help his father's own health. He is a devoted son because the question remains as to what else he needs to do to make them happy.