Can you steal someone's destiny?
It's interesting that Angel doubts whether he's the one to Shanshu. In fact, it's necessary. He should have doubt and doubts. Questioning is the way to the truth.
But we have some interesting outside information on Angel. What do we know? What are the possibilities?
The Oracles acknowledged him as a hero. Were they working for Jasmine? When he turned human, they seemed willing to let him go and were torn about whether or not to make him a champion again. Did Jasmine know that there was another possible miracle coming up or did she think that Angel was her one shot? The visions were sent to him. Doyle was specifically sent to seek out Angel and help him. Lorne sees some interesting things about Angel - including the fact that apparently the whole Darla thing wasn't on 'his path'. Really? That's interesting, in light of the Jasmine revelation.
Wolfram and Hart were destined to sever Angel's connection to the Powers. They succeeded. It was foretold.
What the Vocah says - "The old order passes away and the new order's come. He that was first shall now be last and he that was dead shall now arise." Seems relevant to our current situation.
Also from Vocah: "As it was written they shall prepare the way and the very gate of hell shall open. That which is above shall tremble for that which is below shall arise. And the world shall know the beast - and the beast shall know the world." Again, has application both in S1 and in S4. The Beast?
The specific words of the prophecy that Wesley translated for us are "The vampire with a soul, once he fulfills his destiny, will Shanshu." But it never says just what that destiny is. And Shanshu means both life and death. Wesley guesses at to what it means in that context.
In The House Always Wins, they tell us that Angel's destiny is 'the vampire with a soul' - and got that from Angel himself, when he played away his destiny. Oh, and there's this, too - "Among other things, he's positioned to be a major player in the Apocalypse." Positioned implies that it's the Apocalypse that hasn't happened yet. And it's "the" Apocalypse, like Angel is "the" vampire. But how many threatened Apocalypses have we had?
Consider the actual definition of 'Aplocalyspse' - "A cosmic cataclysm in which God destroys the ruling powers of evil." Well, no wonder W&H isn't that eager to bring it about.
Does this mean that Angel has fulfilled his destiny? The specifics of what he must face - "He has to survive the coming darkness, the apocalyptic battles, a few plagues, and some - uh, several, - not that many - fiends that will be unleashed." Hmm. Have we had any plagues?
Also, interesting note - Lilah was about the day-to-day evil of W&H. Once Angel became about that, she wasn't needed. Lindsey's always been about the epic/prophetic side of W&H. Therefore, when it's time to get into that, it makes sense for him to return.
And key to understanding Lindsey - "I see that you are either the one with the power - or you're powerless."
Now, do I think that Spike's a bit of a wild card? Totally. He chose to get a soul because of Buffy. And we've heard before that the PTB didn't see Buffy coming when it came to Angel/us in S2, so I doubt they saw her coming in regards to Spike. Buffy makes wild cards all the time - she's about breaking the rules of prophecy. Buffy's mere existence past her foretold death messes things up more than once (at the very least, we've got Angel and the First Evil).
Angel's first souling happened before Buffy - and thus could be foretold. Spike's souling happened because of Buffy, and that's why no prophets picked up on the second souled vampire.