During the most recent Monster Hunter: World developer livestream, Capcom confirmed that the game will be getting an expansion. Titled Monster Hunter World: Iceborne, it'll add a new storyline that takes place after the events of the main game, new monsters, new locations, and new equipment. Capcom specifically called it a "massive expansion", so you can expect it to be meaty.
Iceborne is aiming to launch in Autumn 2019, so it's a while away yet. However, the developer says that it'll have more information, including pricing, to share in Spring 2019.
Good news? Get back to the hunt in the comments section below.