The Fallout homepage is now just a countdown clock.
E3 is set to start on June 16th but this countdown is not counting down to then. I can only think that we will see a new game announcement when the countdown finishes.
While looking for potential commented out information in the page source this was found.
PA system failure has occured. Shutdown of the Masterbrain has been authorized and all sensitive materials have been removed for security purposes. Please attempt re-access. Have a pleasant day.
It is rumored to be Fallout4 with the fallout4.com domain having the same countdown. But take a look at this screenshot from Facebook.