Following Princess Kate announcement that she has finished her cancer treatment, one analyst speculates that Prince William and Prince Harry may be planning to reunite.

After years of animosity, the Duke of Sussex's relationship with his brother Prince William became even more strained after he and his wife, Meghan Markle, departed from the royal family four years ago. After Prince Harry and Meghan's Netflix documentary series came out, tensions between Prince William and Prince Harry only grew.

After that, in his first memoir, “Spare,” Prince Harry went after Prince William. But, there's hope for the brothers: the royal family sent birthday greetings to the Duke of Sussex as a gesture of goodwill. According to public relations specialist Ryan McCormick, it might pave the way for a reconciliation between Prince Harry and Prince William.

"As upset as Prince William has probably been at his brother Harry, time has a tendency to mend wounds. William's feelings towards the Duke may have warmed in the wake of Kate's diagnosis,” Ryan told The Mirror.

After receiving her cancer diagnosis in March, Princess Kate has just released a new video to indicate that she has completed her chemotherapy. At this trying moment for the family, Ryan said that Prince Harry might have been "a rock" for his brother.

"The fact that we are seeing more open gestures of goodwill towards not only Harry, but Meghan, I believe shows that a full reconciliation is underway. From a PR perspective, this is very positive development for the duo's brand and a return to Royal duties would be something that I think few would object to,” Ryan continued.

But Ryan cautioned that Harry, as Prince Harry's brother, would need to reassure him that he would refrain from "writing any more tell all books and spilling any more family secrets." Another expert cautioned that the differences between Prince Harry and Prince William are excessively "deep-rooted," contradicting Ryan's optimistic view.

"The strain in their relationship, amplified by the highly publicized controversies and Harry's candid criticisms in his memoir Spare, signals that the rift is likely too far gone for a full reunion,” Michael Levine said, pointing to the Royal Family's recent social media birthday post for Harry.

"Symbolic gestures, however well-intentioned, cannot easily bridge the gap left by years of division and public fallout. The complexities within the Royal Family go far beyond what is seen on the surface,” he went on.

Business Times has reached out to Princess Kate, Prince William and Prince Harry for comments.