What do you think the level of interest was immediately before Stone's "JFK"? It only takes a "spark" to start a raging fire. I think it's DiCaprio that bought the rights to the story/book of a cellmate of one of those Mafia crime bosses. He spilled the beans. A movie such as this starring DiCaprio would be no different than Costner and "JFK". Both actors being "boffo" at differing points in time. Also, the subject matter of their movies being secondary at the time of release. The recent DiCaprio flick being a case in point. It immediately gets nominated for Best Pic, lotsa other Oscar nominations, yet the subject matter is Old Hat. This is all it takes to spur interest.
I'm seeing DiCaprio as One Glove Cop and Tom Cruise as Haygood. We can retrofit the Batmobile from one of the old films as the mystery getaway car. The conspirators who are not Shelley and Lovelady will be played by you and TG as kind of an inside joke for the JFKA community. Gotta work Ruth Paine in there somehow - Madonna, maybe? Alex, if he's willing, will be Rosemary Willis, or possibly Oswald, or possibly both.