Jamaican Prime Minister Andrew Holness pointedly told William in front of television cameras that the nation was "moving on" as an independent country.
"I know that this tour has brought into even sharper focus questions about the past and the future," the Duke of Cambridge said in an end-of-tour statement Saturday.
"In Belize, Jamaica and The Bahamas, that future is for the people to decide upon."
William added he and his wife "are committed to service" and that meant "not telling people what to do" but instead "serving and supporting them".
Barbados formally declared itself a republic in November.
Belize, Jamaica and The Bahamas -- all stops on the royal tour -- are each said to be mulling such a move.
The Commonwealth, a grouping of 54 mainly former British colonies, is headed by Queen Elizabeth II.
In 2018, its leaders formally announced that her son and heir Prince Charles would inherit the role when he becomes king.
But William, second-in-line to the throne, said that "who the Commonwealth chooses to lead its family in the future isn't what is on my mind".
"What matters to us is the potential the Commonwealth family has to create a better future for the people who form it, and our commitment to serve and support as best we can," he added.
The Duke of Cambridge's remarks have stirred a debate on social media, with some people wondering whether the he has withdrawn his support for his father to become the next head of the Commonwealth.
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