The Japan-only Monster Hunter Nintendo Direct has taken place, and it did indeed announce a new title and continue the IP's run on 3DS. Monster Hunter XX (Double Cross) was unveiled, a sequel to Monster Hunter X (Cross) that is known as Monster Hunter Generations in the West. It's arriving in Japan on 18th March 2017, with pre-orders opening as early as November.
Though it will be a standalone new retail release, it should be emphasized that this is really an expansion, which is relatively common practice for the series - they often sell very well in Japan. Localisation to the West is perhaps a doubt for that very reason, especially if the process would take a potential release to late 2017 / early 2018, which will be very late in the 3DS's lifespan.
The presentation is in Japanese, but you can check it out below. Some key features include a large flagship monster which shoots fire out of its wings, and an enhanced Diablos will be a second ominous foe. Beyond that there's a new HUB on an airship, some new companions and NPCs, two new Hunter Styles, and Prowlers will have Aerial and Adept-style moves available. (Hat tip to GaijinHunter for some details)
Another welcome feature, very much suiting the fact this is mainly a standalone 'expansion', is that you can also transfer data from Monster Hunter X (Cross) to play the new content with your existing hunter and gear.
We'll see whether any localisation announcements come; in the meantime this is one for importers to consider. Do you like the look of it?