Prince Philip is a year away from his centenary after celebrating his 99th birthday on June 10. This early, palace royal aides are already making plans for his milestone year in 2021. 

His longevity, however, is raising questions about Queen Elizabeth's own longevity, who turned 94 years old last April. What if Prince Philip outlives his wife and then their son, Prince Charles, assumes the throne? Will Prince Philip be sent to a nursing home?

According to royal expert and historian Marlene Koenig, Prince Philip will definitely not be sent to live in a senior home if his wife passes on ahead of him. The Duke of Edinburgh will likely be staying in Sandringham, in his retirement place and his quiet sanctuary in the Wood Farm. 

Koenig said it will be impossible for Prince Charles to uproot his father and let him live in Surbiton among seniors in a facility. Prince Philip's rank in the royal family will also not likely change if he outlives the Queen and his son becomes the King of England. Prince Philip will not be called the King Father, as opposed to the Queen Mother, as he was never addressed as king.

Prince Philip has been the longest-serving consort in the British royal family but he's not longest-living royal on record. Married to Queen Elizabeth since 1947, the Duke of Edinburgh comes third after Princess Alice, the Duchess of Gloucester, who lived until 102 years old, and the Queen Mother, who died at 101 years old in 2002, per Hello.

The Queen and Prince Philip have survived several challenges together, including the most recent and dreaded COVID-19 pandemic. The monarch and her husband have been staying in isolation at Windsor Castle since mid-March to protect their health. 

This lockdown period has been the longest uninterrupted time they've spent together in one house in a very long time. Normally, the Queen's schedule is filled with trips and moving houses that Prince Philip would much prefer to be in Wood Farm, since he has been retired from public service since 2017. 

Before moving to Windsor Castle, Prince Philip was actually holed up in his Sandringham farm, away from Queen Elizabeth, who needed to stay at her official residence in Buckingham Palace as she performed her royal duties. However, since the pandemic, the Queen hasn't been having royal engagements and royal experts say it might take a while, even years, for the Queen to restart her in-person engagements, due to the health risks, and Prince Charles will be taking over on her behalf.