I'm getting really, really tired of hearing this nonsense. There is NO DEFAULT setting for Next. They are going back to the notion from AD&D, where there are no assumptions for the setting (other than perhaps Greyhawk names on a few spells). Realms is simply going to be released during the first year. Almost certainly Ebberon will follow shortly (maybe early 2015).
I went back to reread some of what has been said on this topic, and I stumbled across an relevant quote from Mearls, said during the 2012 GenCon keynote:
Mearls said:
The key for us, though, comes down to focus. If we focus on one world at a time, that means we can bring it to life in a way that has never been done before. The Forgotten Realms is a focus on new material, but that doesn't mean we're ignoring our other settings. Let me make that very clear: we're focusing on the Realms to begin with, but that doesn't mean that's the only setting we're ever going to do.
We definitely have things in mind for what we want to do with our other settings. We just want to make sure that if we put all of our energy and focus... and really focus on making one great setting, for now, to avoid splintering our attention and giving you six mediocre ones.
All the emphasis is mine. Assuming what he's describing is still the strategy after two full years of development, Shiroiken may be right. Possibly more right than he knew, depending on how good his memory is. In last weekend's seminar, Perkins referred to FR as the "flagship" setting of D&D5. Flagship can mean a lot of things, but one of those things is just "first out of the gate."
What "one world at a time... we're focusing on the Realms to begin with" tells me is that we're going to get a year or two of heavy Forgotten Realms support, and then it's going to stop, followed by /equally heavy/ support for another setting (props, Shiroiken), which will in turn give way to a third setting in 2017-2018.
What "we can bring it to life in a way that has never been done before... really focus on making one great setting" tells me is that we're getting hardbacks, or at least a lot of thick softcovers. That does not sound like "a few articles in Dragon" to me.
And assuming that Mearls wasn't just picking that "six" out of the air, they may actually have a list of six settings they are planning on supporting over the next decade. Which at least gives us a /target/ -- it means we're most likely looking at the Forgotten Realms (already in production), Ravenloft (mentioned at PAX), Eberron (mentioned at PAX), Dragonlance (mentioned at PAX), Greyhawk (called out by Mearls immediately following the above quote, in the 2012 keynote), and Spelljammer (called out by Mearls in the 01 July 2013 Legends & Lore column). That's a solid cross-section. I could live with that.
I also figured I'd link that 01 July column, because I keep referencing it and it'd be handy to have the link in a recent thread. This is the December 2013 reprint:
https://www.wizards.com/DnD/Article.aspx?x=dnd/4ll/2013end1
And this is the really relevant bit, at the end of a 120-word paragraph on the subject:
Mearls said:
...when we talk about Spelljammer as it relates to other settings, we're going to focus on it as its own setting and downplay its role as the connecting tether between various D&D Next worlds.
The depth of implication in that statement gets me every time. The article also specifically calls out Planescape as the "default assumption" for the core cosmology's outer planes.