But the changes have come at a terrible cost for Charles, who has seen his brother Prince Andrew disgraced and his once close sons, Prince William and Prince Harry, become estranged.
The trials and tribulations of Andrew and Harry — one tainted for a close friendship with a convicted sex offender, the other unwilling to continue his high-profile role — will take both out of their royal duties, leaving a smaller, more modest royal apparatus.
"Charles has been saying for years and years, 'Let's make it smaller,'" said Majesty magazine editor-in-chief Ingrid Seward. "He feels quite strongly that with such a big House of Windsor, there are too many opportunities for things to go wrong. And it's too expensive. And they need too many houses, too much public expenditure."
She does not expect Charles to take any joy in recent events, though, particularly because of the breakdown between William and Harry.
"He's very saddened, as any parent would be if their children have fallen out. But I think he probably feels that in the fullness of time, hopefully, it will get back on track," she said.
The royal focus going forward was neatly summed up by a rare formal portrait released two weeks ago by Buckingham Palace to mark the dawn of a new decade: Queen Elizabeth II with her three direct heirs: Charles, 71, William, 37, and 6-year-old Prince George.
It is a serene image of a 93-year-old monarch surrounded by the three people expected to follow her to the throne, and it masks the behind-the-scenes turmoil and disappointments surrounding Andrew and Harry.
Andrew's fall is a full-blown scandal. His conduct has raised ethical issues in the past, but he had managed to retain his royal role until he completely miscalculated the impact of using an extended TV interview in November to defend his friendship with convicted sex offender Jeffrey Epstein, a wealthy financier.
The queen's second son seemed to have a moral blind spot, defending his relationship with Epstein — who died in a New York prison in August in what was ruled a suicide — as honorable. He did not express a word of sympathy for the girls and young women victimized by Epstein.
Andrew still faces possible questioning from law enforcement in the U.S. and Britain over allegations that he had sex with a teen trafficked by Epstein, which Andrew denies, as well as questioning from lawyers representing women who have filed civil suits against Epstein's estate.
When the tempest of bad publicity became unbearable, Andrew announced a decision to step down from royal duties. There was no public comment from the queen or from Charles, who was said by the British press to have advised the queen that Andrew could not continue.
There is no scandal surrounding Harry, but it seems painful for all concerned. Even the stoic queen, who seems to refer to private matters roughly once per decade, has spoken of her disappointment.
With his charming smile and ginger hair, Harry has long been one of the most popular royals, and with his brother, William, was seen as a key part of making the creaky monarchy vital to younger Britons. Much of the world watched enthralled in 2018 when he married Meghan Markle, a successful American actress, at a storybook event at Windsor Castle.
The fairy tale has since fractured. Harry and Meghan, feeling trapped by their duties and warring with the British press, have announced plans to drastically reduce their royal roles and spend much of the year in Canada. In a major breach of family etiquette, they announced their plans without prior approval from his grandmother, the queen, earning a rare display of royal pique from Elizabeth.
Harry seems torn between the wishes of his wife, Meghan, and his fealty to queen and country.
The queen, whose 98-year-old husband, Prince Philip, is ailing, has slowly cut back on her official duties in recent years and passed more to Charles, who often represents her at overseas events. But Elizabeth took center stage earlier this week when she summoned Charles, William and Harry to a crisis meeting at her rural retreat to deal with issues raised by Harry's plan to break away.
Harry's plan puts Charles in a ticklish spot faced by many parents, albeit on a much smaller financial scale. He is in the position to decide whether Harry and Meghan continue to receive money from the Duchy of Cornwall estate, with annual revenue of more than 20 million pounds ($26 million), once they have for the most part abandoned their royal roles.
Collateral damage has included the previously close bond between Harry and William, who hold a special place in many Britons' hearts as the offspring of the late Princess Diana. Many remember them walking silently in her funeral cortege in 1997. William has not commented publicly on the breach, but Harry has said they are now on "different paths."
Removing Andrew and Harry from the equation will leave the monarchy with a smaller footprint: fewer senior royals gathered on the Buckingham Palace balcony to wave to the throngs at national events, fewer to open hospitals and help raise money for charities, and fewer using public funds to pay for official travel and events. There will also be fewer royal households with competing interests.
Until these recent seismic events, the royal entourage has grown along with Elizabeth's family. She is the longest reigning monarch in British history, with four children who have started families of their own. There are grandchildren and great-grandchildren as well. Some have scorned royal titles, but others have not, leading to a proliferation of princes and princesses.
Royal historian and author Hugo Vickers cautions that Charles may be misguided in his plans to shrink the monarchy because the extended family actually provides substantial help.
"I think it's most unwise because other members of the royal family help with a lot of things the monarch cannot do," he said. "He'll soon find he needs to be helped."