"Changes [in his life] are afoot," a source close to William tells PEOPLE. And while most royal insiders believe that he will signal the end of the idyllic life he and wife Kate have enjoyed in north Wales, the question does arise: What will he do next?
Palace officials are set to unveil that decision in the coming weeks, and he has several options: to stay in the RAF; move to another branch of the military (including possibly going back to the original regiment he joined, the Household Cavalry); or to leave service completely.
As a senior palace source tells PEOPLE, that last option, in itself, presents other alternatives. But it's more likely that he will opt for a greater role in the royal family and their public activities, or even marry that duty with a continuing role in the military or something else.
"It's a big watershed moment – whether or not he stays in the services or whether a dynamic role can be created for him," says Queen Elizabeth's biographer and historian Robert Lacey.
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"It would be the truly modern royal thing for him," says an insider. "They are in a position to give back."
Says Ken Wharfe, former bodyguard to William's mom Princess Diana, "The Duke of Edinburgh is aging, the Queen is entering her late 80s, and the Prince and Camilla are not that popular. There was some hesitation about 'Do we push William into a full time royal role?' But now, with him being married and a baby on the way, is the perfect timing."
For his part, William is perfectly placed to step up. "There is no one in the royal family below Charles who can really do the job," Lacey adds.
What is certain, though, is when he flies over the wild coves returning from a mission to nearby mountainous area of Snowdonia, the prince will look with pride at all below.
There, his secluded farmhouse that he has made his home with Kate, and, beyond the quiet beaches where they walked cocker spaniel Lupo.
It is also where he proved himself to be an accomplished helicopter pilot – something that saw his promotion to the equivalent rank of captain and his immense satisfaction at saving lives.
Now, a new life beckons. As the baby's due date of July nears, the couple is working to update their future home, Apartment 1a at Kensington Palace; and Anmer Hall in Norfolk is said to be earmarked as a future country home for the couple (the renovations planned for it by the royal estate have been confirmed by PEOPLE). They are also starting to staff up with a housekeeper being sought and a new general helper and driver already on board.
Whichever direction he takes, William's life in Wales is set to "become a happy memory," Lacey says.