I guess that it's kind of moot now, since the book is about to come out, but unless I missed them, we never got any previews from the new Dragonborn book. Maybe WotC wants to surprise us, since it's a new format?
I suspect the length is the biggest reason - at only 32 pages, they can't give out the usual amount of previews without having given away half the book.
We did get some info in December's general previews, and I vaguely recall seeing a Paragon Path preview or something floating around (possibly an Ampersand or Editorial or similar). But still wouldn't have expected an article or two simply to bring it to people's general attention, even if the preview didn't have all that much.