So, Magic is returning to Zendikar next year, and I have a suspicion (pretty much unfounded) that the recent Unearthed Arcana material would fit well there...and the block comes out around the time a D&D Fall Hardcover would ...I'd love to know how GGtR did... Wyatt says the Plane shift docs are so popular they led the way to the Ravnica book, but is the experiment done? Or is this the start of a line of cross-over books. To me it seems obvious that they should make a setting book to accompany a new Magic card block. Basically instead of doing the art books, make a D&D setting book that includes lots of lovely Magic artwork - two birds one stone.
And really the duplication in effort in world-building seems silly to me. The old D&D worlds were created before the art of world building really came of age (and there's an absolute ton of old material to work with, so it's not like more really needs to be written...). Time to turn the page and move forward in a co-ordinated fashion IMHO.