Knightfall
World of Kulan DM
A lot of people didn't like Eberron. It didn't feel like D&D to them. Personally, it took a while for me to like the setting. It has some excellent story elements and mechanics.I was surprised that Eberron seemed to just sink without a trace. That might be a consequence of the "three books and out" approach WotC took, though FR seemed to remain popular.
I wouldn't mind a new version of Ravenloft. Still, I'm not sure if it can stand on its own. So many of its story elements rely on the various D&D worlds. Do you cut out any references to the older settings, so that DM's don't require a PhD in D&D game history in order to run it properly?Of the classic settings, I think I'd be tempted to re-do Ravenloft, since it's both quite popular and hasn't been done recently. (Also, Ravenloft has existed, in some form, in all editions.)
This is why I think it might be best for Nerath to become the next setting. FR, Greyhawk, and Mystara as well as Dragonlance and Birthright all have their similarities. Instead, build a new setting that takes the best adventure sites and mechanics from those worlds and redoes them in a completely new way.Otherwise, I'd probably go for something new. Eberron and Dark Sun have been done recently, Spelljammer is a bit "out there" to be done so soon, Greyhawk and Dragonlance are a bit 'close' to FR, and Birthright requires the addition of some fairly hefty domain-management systems that they probably don't want to do immediately.
Maybe Greyhawk City enters Nerath under the veil of The Free City, yet their is a Castle Greyhawk nearby. Take the domain-management system out of Birthright and give to Nerath for those that want to go beyond the Conquest of Nerath board game. Maybe take the unique monsters and race from Mystara and embed them into the new world with new reasons for their existence.
Because while I want a revival of those old settings, I'm fairly certain that it isn't going to happen.

You just became my new best friend!Hollow Earth?


I love Hollow World! But can it work without Mystara?
Heh.