Monster Hunter: World isn't done with new content yet. Not by a long shot. There are big things on the horizon for the game, expanding into a new biome, with new monsters, weapons, armor options, and maybe even the odd skill or two. It's called Monster Hunter: World Iceborne, and it's coming in Fall of 2019 as a premium DLC option.
Capcom's flagship monster slaying series has never been a huge hit in the west, but World changed that in early 2018 when it became a mega smash on consoles and later popular on PCs too when it debuted in the Fall of that same year. Since then a number of free content releases have been sent the way of hunters of all types, giving them access to big siege investigations, new and tougher monsters, extra armor, event quests, tie in character cross overs and more.
All of that will continue next year. The first release will be a tie-in with the Witcher series of games. Geralt of Rivea will become a playable hunter, though whether that means special scenarios where you play as the titular Witcher, or whether it will be an armor set like Dante's Devil May Cry crossover, remains to be seen.
That will be followed by the introduction of a few additional monsters throughout the year. Arch tempered versions of Kulve Taroth and Nergigante should provide a bit of an additional challenge to veterans of the series.
The big expansion is coming in Fall of 2019 though. Iceborne will take players to a new continent where new challenges await. The hinted at moster looks likely to be a Nargacuga, though there will likely be other monsters to battle too. Which means more outfits, more weapons, and more grinding away.