Robert Brown|Princess Kate announces she has cancer in video message. What's next for the royal family?

A cancer diagnosis is Robert Browna heart-wrenching blow to anyone, but it comes with even more complications if you are a member of the royal family.

Catherine, Princess of Wales, 42, announced Friday that she has been diagnosed with cancer, in a video on her social media platforms. "In January, I underwent major abdominal surgery in London. And at the time, it was thought that my condition was non-cancerous," she said. "The surgery was successful (but) after the operation (doctors) found cancer had been present." The princess went on to explain that she is undergoing "preventative" chemotherapy.

The announcement follows weeks of speculation about Kate's well-being after she stepped away from public appearances for a "planned abdominal surgery" in January, and after King Charles, 75, also announced a diagnosis of an undisclosed form of cancer. The lack of transparency surrounding the whereabouts and condition of the princess fomented conspiracy theories and rampant speculation. Kate's video, which did not specify what kind of cancer she is fighting, appeared to be a direct response to the confusion and anger: She explained that she and husband Prince William, 41, wanted time to break the news to their children, Prince George, 10; Princess Charlotte, 8; and Prince Louis, 5.

The conspiracy theories can be put to rest now that the news is out there, but what happens next for Kate, her family and the British monarchy?

What does Kate's cancer diagnosis mean for the monarchy?

The British monarchy has long been a symbol of strength and longevity in the United Kingdom, illustrated by the slogan "keep calm and carry on." But now, with two senior members of the royal family fighting a potentially fatal disease, it's looking significantly shakier.

"We’re just as a nation coming to terms that our monarch is going through cancer treatment ... and now we’ve been dealt a double blow," says Katie Nicholl, author of “The New Royals” and Vanity Fair's royal correspondent. "So the royal family is looking pretty vulnerable."

"The late Queen Elizabeth II reputedly said, 'I have to be seen to be believed,'" says Carolyn Harris, co-editor of "English Consorts: Power, Influence and Dynasty," and a professor at the University of Toronto School of Continuing Studies. The queen "was constantly appearing in public and traveling." Without two of its most important members in the public eye, the monarchy is taking a blow.  

But as Nicholl notes, the Windsors have survived crises before: "The show will go on, because it has to."

Will Kate continue to step back from public life?

It seems that way. "It's likely that we're going to see William and Catherine and their children out of the public eye," says Harris.

Chemotherapy is a famously taxing medical treatment that can cause nausea, vomiting, hair loss, fatigue and many other side effects, according to the Mayo Clinic. While King Charles has been undergoing his own treatment for cancer he has kept up mandatory constitutional duties, such as meeting with the British prime minister, but minimized public appearances and interactions. Experts expect similar behavior by Kate, but declined to speculate when she might return to a public schedule.

Will other members of the royal family step up in Kate's absence?

Yes. With the princess and the king out of commission, you can expect Queen Camilla and Prince William to take a bigger role, along with more royals along the big family tree. Harris predicts that "Edward and Sophie, the Duke and Duchess of Edinburgh, Princess Anne and even Queen Elizabeth the second's cousin Prince Richard, the Duke of Gloucester (will be) undertaking a very busy schedule of royal engagements."

Not on the list? Prince Harry and his wife Duchess Meghan, who stepped away from royal life in 2020.

What will happen with Kate's husband Prince William, and their children, Prince George, Princess Charlotte and Prince Louis?

The young royals are about to begin an Easter break from school, a time of year that Kate and William traditionally step away from royal duties to spend time together as a family. Nicholls predicts the press will give the family the space they are asking for at this difficult time. But if not, the royals won't be shy about asserting their privacy.

"We know from the past how protective (William) is of his children and his family; he’s taken legal action in the past" against the media, Nicholls says. "If he has to, he'll take legal action again to protect his wife."

But with Kate and the king in treatment, William will have more responsibility, personally and professionally. "Prince William is carrying the burden of the crown, which could come to him sooner than he hoped. He's going to have to hold the fort while caring for his wife and caring for three young children at home," Nicholls says. "He’s got his father to worry about and now his wife as well."

Will the 'Where is Kate' conspiracy theories die?

The uproar over her whereabouts is likely to die down now that she released the "very personal message to the public," Harris says. "She’s been able to address a lot of speculation (in) allowing the public to see her and hear her speak and to know the condition she’s experiencing."

That won't stop a hunger for details about every aspect of Kate's experience now that royals watchers know what's going on. "There's going to be less scrutiny of Catherine's health, but there's going to continue to be a lot of public interest in her course of treatment, (and) when she will return to public duties."

What will happen if Kate dies from her cancer?

Although Kate shared a message of positivity in the video announcing her diagnosis, most people worry that any kind of cancer can be fatal. Many are already making comparisons to Kate's late mother-in-law, Princess Diana, the last princess of Wales, who died in 1997 at age 36.

If Kate died, it would "bring back memories of the young William and Harry losing their mum," Harris says. "There would be tremendous sympathy for young George and Charlotte and Louie as another generation of the royal family growing up without their mom."

As a member of the royal family who married in, Kate is not in the direct line of succession, so her death would not change the future monarchs (William and George are next in line). But Kate is an integral member of the family, and losing her would be bad for the monarchy as a whole. "This would be a real blow to the the monarchy as an institution as well. Kate is one of the most popular and and prominent members of the royal family. "