* It isn't just Buffy who says the line now runs through Buffy in Season 7. It's also Dawn and The First, and it is perhaps implicit in the words or actions of Giles, Anya, Willow and Xander.
Buffy generally has a superiority complex. Fact is, she isn't the best source of information regarding this as she really doesn't know what is happening, its all guess work.
Dawn, well not being funny but I would never class her as an expert.
The First is a plausible until you realise it isn't as 'Omniscient' as it likes to suggest. Fact is, the First Evil is nothing more than talking air....though i'm more inclined to believe what it says over Dawn the Scoobies and Buffy, we still don't know if what it says is the truth.
* We know the "Faith only" rule to be false, because at the end of Season 7 the slayer line goes all over the place.
What we do know is that pre-chosen there are 2 active Slayers, Post Chosen all potentials are active Slayers. But we have no real understand what that means in terms of the Slayer Line.
* Beljoxa's eye tells us distinctly there is a "disruption in the slayer line".
Yes, it does.
It says the cause is 'The Slayer' then we cut away.
* Giles tells us the "disruption in the slayer line" was caused by Buffy coming back from the dead. Anya tells us it was a result of the spell her and Tara cast.
Yes, but Giles never says that the Slayer Line is now running through Buffy meaning she is THE Slayer.
We make this assumption even though its a pretty sound one, its still only that. We are still unsure exactly what is going on.
* If the disruption in the line does not have something to do with Buffy, then why does the First want to kill Faith, and keep Buffy alive.
Well its been a while since I saw the Angel episode and just as long since her season 7 stint, however the attempt on Faiths life was weak at best.
And, I might be wrong it is 3am, there was only the one attempt in Prison wasn't there?
We still aren't given a definitive reason why Buffy is to be kept alive, apart from the only reason I can think of....its her show.
* There is no interview, or verifiable statement from Joss, or any of the writers after Season 6, stating the line can only run through Faith. Joss said it pre-season 6. Marti Noxon said it way before that, but I've never seen such a statement that would cover Season 7, nor to I believe one exists. Someone always says they know of one, but they can never produce it.
But this doesn't constitute as proof does it?
This just means that no one said on record anything regarding this.
See, i'm kinda on the side of all the information posted above because its all plausible makes sense....i mean its not gonna keep me laying awake at night...i just want to say that, none of the above constitutes actual proof of what was actually happening, its just a theory that has yet to be affirmed by Joss.
It strikes me as strange that this is the most commonly held theory yet no one has said 'Yes, thats it' which leads me to wonder if its not quite the full story and Joss was keeping it underwraps for future spin-offs or this comic.