The irony of the whole "End Of Days' thing was that Buffy died ayhow, and almost exactly how the Amora demon predicted. Instead of giving her life protecting Angel, she gave her life protecting Dawn. Either way, Buffy died protecting someone who she loved.
The "End Of Days" as it was referred to here might be just a generic phrase, meaning whatever version of the apocalypse is currently taking place, or it could have been more personal, referring to, literally, the "End Of Days," as in the last LIVING days for Buffy and Angel, though not necessarily the entire world.
Either way, the Powers obviously took advantage of Angel's concern (one might even say panic) at hearing that he would be responsible for her death. They managedto regain Angel's services without actually changing Buffy's fate in any appreciable manner, since she died anyhow. I've always wondered why Angel never seemed to figure that out for himself