Despite their exit from royal duties and relocation to California over three years ago, Prince Harry and Meghan Markle continue to intrigue the public, with Prince Harry's best-selling memoir "Spare" being a testament to this. However, a royal commentator suggests their approach may not be sustainable.

The topic was broached in Sky News Australia's "The Royal Report," with guest speakers Gemma Tognini, founder of GT Communications, and Bronte Coy, News.com.au entertainment reporter. Host Caroline Di Russo pointed to the Duke of Sussex's memoir's success as evidence of ongoing public fascination with the couple.

Coy affirmed this notion, stating, "Absolutely. We're all still watching," regardless of personal opinions about the couple. She posited that the public's captivation comes from the unprecedented insight into royal affairs provided directly from a member of the family.

However, despite the constant stream of information from Prince Harry and Markle, and the ensuing buzz around them, Coy observed a growing "Sussex fatigue." Yet, she noted the inability of many to ignore the spectacle, likening it to a "trainwreck."

Coy sounded a note of caution about the couple's current strategy, which involves publicizing their struggles within the monarchy through interviews, docuseries, and books. She voiced concerns about the longevity of such an approach, stating, "They burn so bright and so fast with their royal secrets. What is that as a long-term strategy? We're interested, but how long can they grip us for?"

Echoing Coy's sentiments, Tognini admitted to feeling "Sussex fatigue," but confessed her inability to stop consuming the couple's content.

As Forbes reported, Prince Harry's "Spare" tops the bestselling nonfiction list for this year, having sold over a million print copies in the U.S. alone. The memoir offered a candid exploration of Prince Harry's royal life, discussing the impact of his mother Princess Diana's death and his complicated relationship with his family members, including his brother Prince William.

Speculations have been rife following the book's success that Markle may pen her own memoir, especially after the recent dissolution of the couple's deal with Spotify.

Despite claims by British journalist Angela Levin, a biographer of Prince Harry's, that Markle has lost credibility, Levin admits the potential memoir could see considerable sales, as people would be keen to hear her story. "I think there'll be a lot of sales because people would want to know what she said," Levin remarked.