It seems that DeMille's words became something of a self-(un)fulfilling prophecy. In 1983 filmmaker Peter Brosnan and archaeologist John Parker, began a quest to find the ruins in the sand dunes of Guadalupe, California. This new film has nothing to do with them, as far as I know. It's a horror film / conspiracy drama which is partially set in 1923 but also follows the fortunes of a "soon-to-be divorced archaeologist couple Jesse and Alice Carter". According to this movie, the reason that DeMille buried the set was nothing to do with foiling his competitors but because "the set holds the spirit of a vengeful Egyptian god, trapped in a smuggled artifact".It's certainly an unusual premise and I guess it'll be a combination of The Mummy, Stargate and Shadow of the Vampire. There are various interesting characters in the cast, including George Kennedy (from perhaps my favourite film Cool Hand Luke), but the most interesting casting choice, to me at least is that of Dan Castellaneta as Cecil B. DeMille. Castellaneta has made his name in The Simpsons but his face and his normal speaking voice are largely unknown. SO in some ways despite his fame he's a fresh face.
And the interesting thing is that he actually looks a wee bit like DeMille as well. The baldness clearly helps, and the photo of DeMille below doesn't make the similarity as obvious as some pictures of him from around 1923, but nevertheless it will be interesting to see how he plays the role. There's obviously a good deal of footage of DeMille around - not least from the opening to his 1956 remake of the film in question.