The upcoming film version of The Last of Us will be an adaptation of the game's storyline, and not just loosely based on the idea, as is the case with many game-to-movie conversions.
"It's an adaptation of the story of The Last of Us," creator Neil Druckmann told IGN . "As far as where we go and how we make it fit into a film, how it takes into account the unique properties of film... We're not sure yet. We're only just scratching the surface."
Presumably that means we can expect to see both Ellie and Joel on a similar quest for survival.
Most movies based on games retain little of the source material. The just-released Need for Speed movie has some great gaming references, but isn't based on any particular game, and even the popular Resident Evil film franchise has made a name for itself separately to the game story lines.