I think that expecting more than one new area total is a bit much, especially at the level of detail and interactivity that they're pushing here. The announced and expected biomes support a good variety of monsters as is, so they'll simply be shuffled into the existing lineup like they were always meant to be a part of that area.
Yeah, and this is a big reason I would like to know how long they plan on supporting the game post-launch.
Given the circumstances behind this series history thus far, Capcom is an unique opportunity to expand a series that's already a great fit for the GaaS service concept into something truly special.
The small (but often) bite-sized offerings the handheld entries received post launch were something I really enjoyed about them, and I would like to see it continue into World. However, now that we find ourselves at a console-level again, I think that changes a few things.
Content is king in a game like MH, which is why I imagine topics like monster count are still a highly discussed subject here lol, and these days content is often spread out across a larger portion of time in order to keep the player base satisfied while providing a consistent reason to return to the game, and while the smaller sized offerings might have been cool on a portable, I feel when your comparing it to it's peers on a console level, or furthermore a GaaS level, it will come up short if that's all there is.
So, in order to prevent those optics, I believe Capcom has a long plan for MHW that is on a level above what we have seen previously, hence the several areas as DLC rather than one guess earlier. If they combine the smaller updates approach with a consistent but slower release of larger more "traditional" DLC, I think they have a winning recipe for a MH game people are playing for a while.
I also believe a lot of the groundwork that has gone into building this game was done so with the ability to quickly produce additional content in mind.
Of course pricing is a different subject, and I could be wrong, but if I'm right then I could easily see MHW being supported for years to come not unlike we have seen with games like Rainbow Six: Siege.