Dominaria is The Original Plane. For nearly all of the first ten years of its existence, Magic blocks were set on that truly massive plane (how big was it? So big that a single continent on it was able to provide the background for both Odyssey and Onslaught blocks - meaning that at least an entire continent escaped the Phyrexian invasion and the ensuing devastation). Sure, there were short excursions to Ulgrotha, and later Rath (which got overlaid on Dominaria anyhow during the events of Planeshift) and Mercadia, but Dominaria was always where the real action was, even when it was only a throwaway reference.
Then came Invasion block, of course, which brought years and years of storyline - the entire Weatherlight Saga - to a head, and by the end of it all the peace of the grave had fallen on Dominaria. It was time to move on to the metal world of Mirrodin, and thence to explore a new plane every block. Of course, this resulted in mixed feelings initially, but the playerbase loves it now.
Unexpectedly, in 2006, the fall set was Time Spiral, which began a "nostalgia" and "time" themed block about a post-apocalyptic Dominaria. After Future Sight was over, and the time rifts and the sparks of planeswalkers were Mended, it seemed as though the world was done for good. Players got the impression that R&D had grown tired of Dominaria and had in effect written it out of the lore.
Then, on September 17, Mark Rosewater got a question he probably gets very often on his Tumblr blog. User jsttu asked him, "Could we see a return to Dominaria? it's been far too long since we've seen it, and it has likely had time to recover from Time Spiral by now."
Since Mark is often hesitant to give real yes-or-know answers, and having answered similar questions with "maybe" in the past, he decided to put it up to his readers:
Okay, Question Marks, do you all want to return to Dominaria?
The response was overwhelming: In the span of a day, the post got 178 notes (a typical post on Mark's blog gets in the neighborhood of 5-20). Almost every text response was a "yes."
Reader plab719 cited the everything-old-is-new-again principle, saying "I believe it would be worthwhile. By the time we get to back to dominaria it would be a new plane to most players anyway."
Other users shared concrete ideas for the new take on the setting: outcastace said "Absolutely! I think that the devastated state that it was left in after Future Sight lends itself perfectly to a number of potential story arcs and themes. I’d love a “primitive/stone-age” block and at the end of it you discover that it was on Dominaria," while vahnt responded "Yes! I know the world is pretty messed up, it would be mindblowingly awesome for *us* to rebuild the most storied plane in Magic. Alternate win-cons could be everywhere; either win the struggle for resources, or build something to outlast you."
There are proven examples of Blogatog readers influencing Magic design already - Chandra, Pyromaster's "immediate card draw" 0-loyalty ability was derived from reader suggestions, for example. Of course, it's certainly not spawned anything as huge as a whole block yet; but with the responsiveness that Rosewater has to his fanbase, it seems more and more likely with every note on the post.