In a post on its official site, Capcom announced that sales of Monster Hunter World: Iceborne have surpassed four million units. That number was hit thanks to the recent launch of the PC version of the expansion, which has been available for roughly five months on consoles. In addition to that, sales of vanilla World are now at the 15 million mark. The continued success of this series in the face of its reinvention for modern consoles is likely making Capcom very happy.
The company didn't state which version of the game performed the best, only noting that combined sales across PS4, Xbox One, and PC in both physical and digital formats have reached this number. Regardless of where players are predominantly playing, World is continuing to set records for Capcom. It will likely take another surprise hit to dethrone World as the company's best selling game of all time.
As for 2020, Capcom has reiterated that it will continue to support Iceborne throughout the year. An upcoming VR attraction at Universal Studios Japan will allow fans to engage with the brand in a new manner and a Hollywood film set to release in September will let players see their favorite monsters on the big screen. 2020 is going to be a banner year for the series and World is to thank for bringing it to a wider audience.
It is definitely too early to be talking about, but a potential follow-up to World would be a nice way to end 2020. Obviously Capcom is putting some work into designing what a true sequel would be, but just an announcement or teaser for World 2 would be amazing. Capcom has done such a great job reinvigorating the series that it shouldn't rest on its laurels for a continuation.
I'm not quite sure what else could be done. The past history of the Monster Hunter series has seen Capcom iterate in small steps, resulting in sequels that felt nearly identical. Simply repeating that for World 2 would be a big mistake. The reason players have enjoyed this new version so much is for all of the gameplay tweaks it introduces to the core Monster Hunter loop. Capcom doesn't need to reinvent the wheel, but it should look at adding some meaningful changes when sequel time comes.
Source: Capcom IR