Dan Brown, where have you gone?

Like countless millions around the world, I thoroughly enjoyed reading the Da Vinci Code by the author Dan Brown.
I have also read and enjoyed all his other books, Angels and Demons ( looking forward to the film release this year- can't wait to see how they interpret the ending!!) Deception Point, and Digital Fortress. To the best of my knowledge, he hasn't written any more books.
On his website, around two years ago, I noted that his wife was researching for his next book which again would have Langdon and Sophie as the central characters, and the story would be based around hieroglyphics and Egyptology.
Since then, nothing seems to have developed.
On behalf of myself and the millions eagerly waiting to read the new book, hurry up Dan!!!