Prince William, Prince Harry, Meghan Markle and Kate Middleton
The survival of British monarchy will depend on Prince William, Kate Middleton, Prince Harry and Meghan Markle. Pictured: Prince William, Prince Harry, Markle and Middleton arrive at Westminster Abbey to attend a service to mark the centenary of the Armistice in central London on Nov. 11, 2018. Getty Images/Paul Grover

The future of the British monarchy will reportedly depend on Prince William, Prince Harry, Kate Middleton and Meghan Markle, according to one author.

The monarchy will change at the end of Queen Elizabeth II's reign. Many believe that its survival will depend on the fab four. According to royal author Ted Powell, the Duke and Duchess of Cambridge and the Duke and Duchess of Sussex have already brought new topics and interests into the spotlight, including mental health and female empowerment. The way these four royals will stay in touch with the modern world will determine the future of the crown, according to the "King Edward VIII: An American Life" author.

"William and Kate and Harry and Meghan will dominate the centre stage for the House of Windsor for years to come, and the survival of the British monarchy will depend on their charm and charisma," Powell told Express.

"It is exciting to see this new generation of royals developing their own agenda for the modern world, with their emphasis for example on mental health and well-being, green issues and conservation, and equality issues."

As for the future of the royal brothers, recent reports claim that Prince William and Prince Harry are considering a formal division. Now that the both of Prince Charles' sons have a growing family, they will reportedly create separate courts.

Prince Harry, Prince William and Middleton have been working closely together in the past years. In fact, they have been dubbed as the "royal trio." However, Markle's arrival has changed this.

"The arrival of Meghan has changed the dynamic of the relationship in a fairly significant way," royal author Sally Bedell Smith told People. "It is inevitable and practical because it gives Harry and Meghan some freedom to build up their own collection of interests and charities."

Other sources claimed that Prince Harry and Markle are leaving Kensington Palace because they want to have a bigger space when their child arrives. However, there were also reports claiming that the couple didn't want to live near Prince William and Middleton.

"But there has been a bit of tension between the brothers. Now Harry and Meghan don't want to live next to William and Kate and want to strike out on their own. They need more room and hope Frogmore Cottage will be ready in time for when they have the baby," an insider told The Sun.