From http://www.enworld.org:
Mike Schley is a cartographer who has worked on all of WotC's D&D 5th Edition adventures so far, so when he asks "Who's up for an Expedition to the Ruins of Greyhawk? Working on a new legacy map release coming soon."
it's worth taking notice. He also mentions - though I don't think this is connected - that "Here's today's teaser: I'm currently working on my biggest, most ambitious project to date. Lips are sealed but it's going to be awesome."