"Uncharted 4: A Thief's End" will indeed have multiplayer, according to a new preview in Game Informer magazine (via Gematsu). The GI feature isn't online yet, but Gematsu gleaned several details from the issue, confirming that multiplayer will be coming back to the franchise.
The game is set three years after the end of "Uncharted 3: Drake's Deception," and begins when Nathan Drake's long lost brother, Sam, arrives to interrupt Drake and Elena's new-found domestic bliss. Obviously very pleased to learn that his brother is among the living, Drake returns to the life of a treasure hunter.
Sam will be controlled by AI, and is described as very similar to Ellie from "The Last of Us." Naughty Dog said it wanted to explore what it's like to travel with someone as skilled as Drake, and Sam's resentment of his brother's abilities is a point of contention between them.
The brothers make a trip to a fabled Madagascar colony allegedly founded by pirates: Libertalia. The course of the game will take you from this Indian Ocean destination through urban and snowy environments, and will see the Drake brothers square off against two rival treasure hunters, Rafe and Nadine. Along the way, Drake must deal with Sam's unruliness and more intrusion from various villains.
But Drake will also have more tools to play with, which he can put to use hunting artifacts; some artifacts may include notes helping you find others. Environments will be less linear, too, so you have a good reason to use Drake's various abilities.
"Uncharted 4" has been in development since "Uncharted 3" released in 2011, although it wasn't until after work on "The Last of Us: Left Behind" concluded that a proper team was set to task on it.
"Uncharted 4: A Thief's End" is due out on PS4 later this year.