The article is leaving a few bits of information out. For example Matthew Barun has been an ambassador - to Sweden, yes I had to look it up to know for sure. The second thing Anna Wintour, I can find no direct quotes on the subject, it all "A source said" and even those sources say she in not interested in London but Paris - which at least seems logical to me. In terms of a reward, she has been a major fund raiser for the Democrats for years. She will not get this just because Obama won.
All that aside, although posts to Paris and London have prestige, the ambassadors do next to nothing in countries with long term close friendships. A bit of culture showing off, attend the odd state ball. Come out with some flowery complimentary statement about the country as required. Generally if anything big comes up the two leaders talk directly anyway