I'm copying my post from the old thread!
My model is, and hear me out... the Fast and Furious franchise. In 2009 they made a slight comeback with the original cast and good box office ($155M domestic, $208M foreign). Those are numbers very similar to FC. Although FC didn't bring the original cast back together, it was sort of a return to form for the fans and generated some good will for the franchise. So then in 2011, Fast Five came out, built on the previous movie, and ended up with $210 domestic and $416M foreign (!)
I'm not super convinced that DOFP will suddenly send the X-Men franchise into the stratosphere because it has never broken out that far yet, but I do think it'll do very well. It also has a wonderful release date (The Dark Knight and the final Harry Potter film can attest to that). In these early stages, I would predict the following:
Opening weekend: $125M
Domestic (final): $300M
Foreign (final): $500M
I might be totally over-exaggerating, but foreign grosses have become ridiculous these days.