She will remain a princess of Sweden, and in the order of succession. She will continue to receive her appanage (allowance.) Christopher O'Neill will "support" the princess when she carries out official engagements. He will also accompany his wife to official royal events.
Princess Madeleine will not apply for American citizen, and O'Neill, who has joint American and British citizenship, has no plans to become a Swedish citizen. (The United States does not recognize dual citizenship, but it does recognize that other countries allow for dual citizenship.)
Christopher O'Neill is Roman Catholic. He is not required to join the Swedish Lutheran church.
The decision on Christopher's title will be made at the time of the wedding. The couple plan to live in New York City after the wedding.
Princess Madeleine is also the Duchess of Hälsingland and Gästrikland. At the time of her first engagement to Jonas Bergström, the court announced that Jonas would be styled as Duke of Hälsingland and Gästrikland after the wedding.
Mr. O'Neill is not prevented from having a title, or even inheriting a title. The U.S. Constitution is clear about Americans and titles:
"Clause 8. No Title of Nobility shall be granted by the United States: And no Person holding any Office of Profit or Trust under them, shall, without the Consent of the Congress accept of any present, Emolument, Office, or Title, of any kind whatever, from any King, Prince, or foreign State."
A select number of former Presidents and Secretaries of State have received honorary knighthoods from Queen Elizabeth II. This honors were granted AFTER the men left office
William Jennings Capell, 60, is the heir presumptive to the 11th Earl of Essex, who is 68 and unmarried. Mr. Capell is Yuba City, California, grocer.
In 1987, Rick Whortley, a resident of Maine, learned that his father's second cousin had died, and he was now the 5th Earl of Wharncliffe.
Lord Wharncliffe's son Reed is Viscount Carleton. It is unlikely that the family uses the titles in every day life in Maine, but Patrick was not barred from inheriting the title. He did not lose his American citizenship.
Sir Jean Ivor Dunbar of Mochrum, 13th Bt, served in the U.S. Army. He succeeded to the baronetcy in 1977 and died in 1993. He was an American citizen. His son succeeded as the 14th Baronet, and is Colonel Sir James Michael Dunbar of Mochrum. He reached the rank of Colonel in the U.S. Air Force. He his two sons, the elder is the heir apparent. This baronetcy will continue to stay with the American descendants.