Exactly my thinking. Bethesda has never been a group to waste things, and wasting time and money on repeatedly renewing a trademark they don't intend to use as a deliberate mislead or simply letting it go just doesn't fit in with the group I've been following since 2003.
Aside from which if we as a group were, like me as an individual, to assume a high degree of intelligence throughout Bethesda, then we would know they know that Elder Scrolls is (generally) both fan- and critically-acclaimed, and a cash cow. Collectively, it all comes together into a large, unified theory, at least in my brain:
Oblivion was a "back to basics" approach for TES, where the story was tightly focused on a single thing much like Arena, but it was Mehrunes Dagon himself instead of one of his pawns, at least on the whole. Now that means that Dagon's decades-long gambit for Tamriel has been foiled, and he needs to lick his wounds for a few centuries before trying again. The books are shaking up the status quo further, meaning that, like before Daggerfall, the stage is set and they can start from scratch. If we assume that they are using a pattern, that means that the next game will have far less central focus, far more freedom of choice and movement, and will also be very, very, very big.
This leads me to believe that Skyrim will be as close to Daggerfall's scale and scope as they can manage in a modern game, which is why it is taking so long for them to gather sufficient complete parts to announce in style. It will take time to make it even that far, but it will be so worth it.