Even the suggestion is absurd and disgusting. People serve for decades in the foreign service to get promoted to the position of Ambassador - they are well experienced and well trained, and deserve the position due to their qualifications and skills as diplomats.
Apparently the US is notorious for appointing random Presidential supporters and donors as Ambassadors all over the world. In general other countries do not do this (although unfortunately the ultimate 'top-jobs', like being sent as Ambassador to Washington) because they appreciate that your Ambassador should be a skilled career diplomat and not just some random person who happens to be well connected. That's nepotistic and revolting.
Besides, what did Anna Wintour do to even be considered? Did she donate millions for his campaign, or is she going to put Michelle Obama on a Vogue cover