No way the Dunyain have their own Hari Seldon Prophecy.
I wasn't implying that Kellhus would fail his mission, only that the mission as he knew it might have been a lie right from the start. If the Dunyain truely tried to send him to Shimeh, then they probably guessed that he would make it, but I just don't think that was their initial intent.
Like SOA mentioned, as far as we now the Dunyain don't factor in metaphysics into their causality chain. I'm saying that regardless of what the initial intent of sending Kellhus into the world was, none of them could have correctly predicted Kellhus becoming what he is. Which, imo, includes some Hari Seldon/Dunyain Nostradamus.
The only way they could have foreseen Kellhus' ascension would be if they were working closely with either the Nonmen, the Consult (extremely unlikely), a select few World-Born (also unlikely), or if they had secret Dunyain agents in the world already.
Even if the Pragma (or whatever the ruling caste is) knew about magic and the outside, I still have some doubt that they could have done it... Though I would allow for them being able to predict it all if, and only if, the end-game was to forge Kellhus into the only Self Moving Soul.