The House of Oldenburg has not died out at all. The Danish branch of this North German dynasty became extinct in 1863. Christian of Schleswig-Holstein had been previously chosen as heir to the Danish Holsteins, although his wife Louise had a much closer claim to that throne.
In 1918 the last Grand Duke of Oldenburg, Friedrich August, renounced his crown at the collapse of the German Empire. He died in the 1930's and was succeeded as Head of House by his onmly surviving son, Hereditary Prince Nikolaus, who in turn was succeeded as Head of House by his eldest son, Duke Anton Günther, who remains in this position and quite alive. I saw and photographed him last year at a royal funeral. His son, Duke Christian, is married and has four children, among them three boys. In fact there are 14 male Oldenburgs all with dysnatic rights alive today.
Further information can be obtained from: THE GRAND DUCAL HOUSE OF OLDENBURG: German Royal and Princely Families, Volume XXV - Eurohistory.com, Oakland, CA 2005.
Arturo Beéche