My guess is that they'll announce 5th edition is being worked on at this point. The special guests will be the design team:
Mike Mearls: Mike is the senior manager for Dungeons & Dragons R&D. He has also worked as a designer and columnist for the weekly Legends and Lore column. His recent D&D credits include Player’s Handbook 3, Hammerfast, Monster Manual 3, and the Castle Ravenloft board game.
Monte Cook: Monte has worked as a professional writer and game designer since 1988. Monte was one of the three principal designers of 3rd Edition Dungeons & Dragons and the d20 system. He has worked on numerous RPG products, and has published two novels, numerous short stories, countless articles, and a comic book series for Marvel.
Rob Schwalb: Rob is an award-winning game designer who has contributed design or developed over one hundred roleplaying game titles for Dungeons & Dragons, Warhammer Fantasy Roleplay, A Song of Ice and Fire RPG, Star Wars RPG, and the d20 System.
Bruce Cordell: Bruce is an Origins and ENnie award-winning game designer whose long list of professional credits includes Gamma World, Dark Sun Campaign Setting, Forgotten Realms Campaign Guide, Prince of Undeath, and Open Grave: Secrets of the Undead. Bruce is also an author of Forgotten Realms novels, including the Abolethic Sovereignty series and Sword of the Gods.
Greg Bilsland: Greg is a producer for Dungeons & Dragons at Wizards of the Coast, where he works on developing content for D&D Insider and the D&D Organized Play programs. His design credits include the Forgotten Realms Player’s Guide, Monster Manual 2, Monster Manual 3, and Vor Rukoth. He keeps a gaming blog at gregbilsland.com and is active on Twitter ([MENTION=15433]GregB[/MENTION]ilsland).
Jeremy Crawford: Jeremy is the lead rules editor for Dungeons & Dragons at Wizards of the Coast. His design and development credits include the Rules Compendium, all the other books in the Dungeons & Dragons Essentials line, and Player’s Handbook 1–3. Jeremy also co-hosts the official Dungeons & Dragons podcast.
Chris Tulach: Chris is the Dungeons & Dragons program manager for Organized Play at Wizards of the Coast. He is responsible for the development and deployment of Dungeons & Dragons organized play programs, including D&D Encounters and D&D Lair Assault. He is also the co-author of Kingdom of the Ghouls.
Chris Lindsay: Chris is an assistant brand manager for Dungeons & Dragons, where he contributes to the direction of the future of the D&D brand. He has been playing and DMing D&D for most of his life and has been constantly involved in organized play for over a decade. He has also contributed to the design and development of dozens of organized play adventures and D&D products, most notably adventures for Legacy of the Green Regent and Expedition to Undermountain.
Shawn Merwin: Shawn is a technical writer and freelance game designer. His design work for Wizards of the Coast includes Assault on Nightwyrm Fortress, Dungeon Delve, “Backdrop: Moonshae Isles,” and the upcoming Halls of Undermountain.
Matt James: Matt James is a freelance writer and game designer for companies such as Wizards of the Coast and Open Design (publishers of Dungeons & Dragons and Kobold Quarterly respectively).