Finally, we're in the Vault. Time to solve this mystery once and for all.
Hardin and the Board members wait anxiously, and a pre-recorded holograph of Seldon appears before them.
Seldon opens by saying he can't see them, can't properly greet them, and doesn't even know if anyone is in the room. So, smoke'em if you've got'em, or have a snack, or whatever: holographs don't care
Then the bomb drops. The Encyclopedia Galactica is a fraud. He never cared if it ever was completed. Da-da-DUM.
Its only purpose was to keep everyone, including the people of Foundation, from noticing Seldon's true intentions.
Now the people of the Foundation have been cut off from the Empire by the growing power of the Periphery Kingdoms.
Also, they can't know Seldon's Plan in advance because to know the plan means a chance they could change the plan. They just have to go with the flow of time and know that they're building toward the next Galactic Empire.
Super weak of you Seldon. Super weak.
So what choice do the people of the Foundation have? There is only one "action—that is, the solution to your dilemma—[and it] is obvious" (II.7.27).
After Seldon's recording ends, Pirenne turns to Hardin and admits he was right: the Board needs to give up control.
The obvious solution, it seems, was only obvious to Hardin.