I cannot believe some of you didn't like the finale. Just in case this is posted somewhere else and I'm an idiot I'm sorry, but I just wanted to prove Rambaldi's prophecy (see below).
-Every question I can think of WAS answered:
1. Irina's agenda was ultimately the same as Sloane's: to finalise Rambaldi's work, and gain eternal life. To do this she manipulated anyone she could, including Sydney, to get as many Rambaldi artifacts and clues as possible to finnish his works.
2. Sydney was trained for the CIA not just because Jack wanted to prepare her for people like her mother, but because of the puzzle she solved, a call-back to season 2, where the puzzle was linked with Project Christmas, which prepared Syd for CIA/SD-6, but was never fully explained.
3. Rambaldi's prophecy WAS correct to the letter. Sydney and Nadia fought over the device back in season 4, and now in season 5, Nadia did not survive: Rambaldi was never specific as to when it was that one of the two would die. Whoever said before on this forum that Sydney did bind his works with her fury was right because she was so driven by Sloane, but as mentioned at the end of the previous episode, she ended up giving Sloane everything he needed to "bring the greatest power unto utter desolation".
Now we're assuming that desolation means 'destruction' etc, but it DOESN'T. Not here anyway.
The prophecy goes:
"This woman here depicted will possess unseen marks. Signs that she will be the one to bring forth my works. Bind them with fury. A burning anger, unless prevented. At vulgar cost, this woman will render the greatest power unto utter desolation."
So, everything up to from the bit where it goes "at vulger cost..." works out fine. Here's why it works from there on: Sloane was the 'greatest power'. Rambaldi called him that because he knew Sloane would be the one to actually realise his dream, something he believed in as passionately as Sloane did, thus calling him, and indeed himself, encased in the tomb, the source of eternal life, 'the greatest power'. Because of events that SYDNEY set in motion because of her fury, her need to end this, to take out Irina, to make the world safe for her baby, she left Jack, and Jack blew the tomb up, burrying his corpse and Sloane's ever living body forever, entombing them. One meaning of the word of "Desolation" is: "the state of being decayed or destroyed" (taken from a dictionary. THE OTHER MEANING OF THIS WORD IS: "sadness resulting from being forsaken or abandoned".
Surely this is self explanetory:
By "Greates power" Rambaldi meant nothing of the world today, or human activity, he meant himself, and his followers, follwing himself the known, acknowledged Rambaldi way of thinking. Sydney gave Sloane everything he needed as a result of being so desperate to end him. When Sloane was left in the tomb, he was abandoned, by Sydney, Jack, Emily, and at the very end, Nadia, so that the writers could emphasise his abandonment.
Everything in the prophecy came true. If you have anything else that you don't understand then try me. If you just read all that, I appologise, because you must be like 100 by now.
I loved the finale so much, and I love Alias.