Mike said if a world or plane isn't mentioned to assume it's still there.It's not my version! It's just an attempt to draw what Mearls described. He didn't mention the Outlands.
First, welcome to EN World!
Second, I haven't seen the adventures, but the novels ended with Ao destroying the Tablets, not because they were fraudulent, but because they outlined each god's position and duties - with Bane and Myrkul stealing the Tablets, it was the last straw in the gods shirking their responsibilities in favor of self-aggrandizement. Hence, Ao destroyed the Tablets largely in disgust for how the gods had been acting.
Given that, he's now recreating them to lay down the law for how things will be from now on.
I won't even get into the various small instances of Dark Sun material that was to be found in the products for other campaign settings (e.g. an Athasian life-shaped artifact in Tcian Sumere - the fortress of Tenebrous (that is, Orcus) on the Negative Energy Plane in Dead Gods).
Given that the changes to FR this time were conceived, planned and largely driven by R. A. Salvatore and Ed Greenwood, I'm guessing they have a passing familiarity with it.It makes me wonder if the designers for d&d next have actually read the source material they're basing from.
If I said what I think of this decision, I'd probably be banned from EN World. And possibly the Interwebs.
Heck, Ravenloft doesn't even have to be a plane. Just make it a collection of horror themed places, like Transylvania is depicted in Stoker. I'm not sure the whole mists thing really adds to it for me.
Btw, is there any other way to do multi quote? I've just been using meta tags.