According to The Hollywood Reporter, American Crime Story creator Ryan Murphy has optioned Jeffrey Toobin's 2000 book A Vast Conspiracy: The Real Sex Scandal That Nearly Brought Down a President, as source material.
Toobin's book The Run of His Life: The People v. O. J. Simpson was the inspiration and source material for the first season of American Crime Story, which focused on O.J. Simpson's murder trial, and Toobin himself acted as a consultant to the writing staff for the critically beloved and wildly popular first installment.
Murphy and Brad Falchuk's American Crime Story Season 2, slated for 2018, is reportedly going to focus on Hurricane Karina and then be followed six months later by a Season 3 that tells the story of Gianni Versace's murder in 1997 (in which Lady Gaga will not play sister Donatella). So presumably the Clinton scandal arc would be reserved for Season 4.
With political scandals and conspiracies being hotly debated on both sides of the aisle in recent months and partisan divides deeper than ever, it's hardly surprising that the property was snapped up.