On July 23, Will Smith gave reporters an early preview of his upcoming thriller Gemini Man, in which the star fights with a younger clone of himself. The 50-year-old actor noted that, with advances in visual effects, he could sit back and let a digital double do all the work. "There's a completely digital 20-year-old version of myself that can make movies now," he quipped. While the comment got a laugh, it wasn't too far off from Hollywood's new reality: Actors can now play a character at any age — regardless of their own.

New VFX techniques could be used to tell stories that studios might not have attempted just a few years ago. It's not too difficult to imagine in the near future, say, a digital likeness of an Avengers star appearing in Marvel Studios' ever-expanding big-screen universe in perpetuity, even if the actor has long moved on from the role. And who profits from these digital copies of actors will likely spark union debates as usage grows more common.