A new expansion to Monster Hunter X was revealed in the Monster Hunter focused Nintendo Direct earlier, titled Monster Hunter XX. The Direct was Japan only, so the title is currently only announced for Japan and not the West as of yet. You can watch the reveal trailer here:

And a more in depth discussion of all the information in the Direct here:

There’s a lot of new content to be had. Two new flagships and two returning monsters have been confirmed, alongside a new HUB, a town floating in the sky on balloons. As well as that, G rank has been added, along with G rank appropriate gear and difficulty. The given release date is in March, which would mean that it’s being released in the same month as the new Nintendo Switch. This could point to a longer lifespan for the 3DS, but it’s likely that we could see a port to the Switch at a later date.

You’ll probably know Monster Hunter X by its localised title, Monster Hunter Generations. We received it just a few months after the Japanese release of the game, so we can probably expect a similar launch window in the West for this new expansion as well.