Not in the mid-1980's, of course, but I can't imagine a better person to make a film of A CHORUS LINE now than Rob Marshall. He comes from Broadway and likely knows the material backward and forward, he clearly has experienced Broadway auditions on both sides of the table and he has experience taking a stage-bound show biz story and making movie magic with it. The problem would be that, I think, the material in A CHORUS LINE is resistant to being pulled apart and rewritten and changed...every word, note, and lyric is so interconnected that, once you start pulling it all apart to make changes, you risk all the dominos falling. And that IS a problem with the film.
Marshall wouldn't be able to make the kind of changes to the material that he made to make CHICAGO work on film without risking another debacle like the 1985 version. He'd have to commit to working with the material as it is, and that might feel too constraining to a director who wants to interpret material in his own way.