It now looks like the final worldwide first-release box office for The Avengers will be very close indeed to $1.5 million, as projected here, and doubtless elsewhere, a few months ago. It opened most recently in Japan, where it had already earned considerable money from previews, and where it can still be expected to bring in some serious revenue after its first two (quite strong) official weekends in the cinemas.
On the other hand, it has pretty much run out of steam elsewhere, including in the US.
Box Office Mojo is currently giving a worldwide figure for The Avengers of $1,491,849,983 - with a bit more to come in from Japan this weekend (and in succeeding weeks). With not much coming from anywhere else, and assuming there's no vital fact that I'm missing, the final worldwide figure will be just about, but will not exceed, $1.5 billion. I doubt that anyone expected that before it was actually released. We all thought it could do well, but it's become a box-office monster.
For whatever reason, The Dark Knight Rises has performed relatively poorly in the US (we can project that it will end nearly $100 million behind The Dark Knight). On the other hand, its non-US sales have been very strong, if nowhere near as strong as those for The Avengers. All this gives it, at the moment, a worldwide total of $960,516,000. Once all the figures for this weekend are announced, it should be getting to around $970 million, and this is only its seventh weekend in American release.
Thus there are still few weeks to go before it, too, runs out of steam; so it looks as if The Dark Knight Rises will gross over a billion dollars (but probably not "well over"). Given the enormous expectations attached to it from the start, this is a relatively disappointing performance, though it is still going to be a very, very profitable movie.
Edit: See my comment below about how I spoke too soon. Mea culpa. With the latest data, The Avengers has indeed squeaked over $1.5 billion, and The Dark Knight Rises may yet get into "well over" $1 billion territory.