American Ancestors, one of the two periodicals of the New England Historic Genealogical Society, there is an interesting article titled The Ancestry of President Donald John Trump. An Initial Exploration, written by Alexander Bannerman, Julie Helen Otto and Gary Boyd Roberts.
Gary Boyd Roberts is Senior Research Scholar Emeritus at NEHGS and is well-known for his book Ancestry of American Presidents, which was printed in 2009 and reprinted with corrections in 2012 (ISBN 978-88082-220-6), and which I (of course!) have a copy of. Julie Helen Otto, a former Staff Genealogist at NEHGS, is currently responsible of indexing the New England Historical and Genealogical Register (shortened to The Register) and serves as transcriber for Mayflower Descendants (which is not included in the membership subscription to NEHGS).
Alexander Bannerman is the editor of the periodical Executive Papers, which is the journal of The Hereditary Order of the Families of the Presidents and First Ladies. An ancestor table for Trump will appear in issue 14 of Executive Papers. The said table will be more detailed than the one published in American Ancestors. The Trump family can be traced to Kallstadt in Germany, while the president's mother was born at the Isle of Lewis in Outer Hebrides in Scotland. Some genealogical information about the president has been published on various webpages, including ThoughtCo.com.
According to the Icelandic genealogist Oddur F. Helgason, Trump is a descendant (of among others) the Norwegian King Håkon V Magnusson, cf. Iceland Monitor 24 Janyar 2017, but I would like to see more details of his sources before making further comments.
Parts of the latest issue deal with early Cape Cod ancestry, as demonstrated on the front cover. Besides the Trump article, I also found the article Bringing the Armenian Genocide to Light by Ann Goolkasian O'Donnell to be particularly interesting.