In southern Syria’s chilly late winter of 2011, a scrap of schoolboy graffiti that read “Your turn, Doctor” — a mocking call for the ouster of President Bashar Assad — helped spark a ferocious civil war that has left hundreds of thousands dead and millions displaced.

Now, there is a growing diplomatic consensus that Assad, the 51-year-old ophthalmologist who inherited Syria’s leadership 17 years ago from his dictator father, has almost certainly prevailed against efforts to dislodge him militarily — and that his opponents need to come to terms with his political survival as they plot a new course.