This is what I think'll happen.
Some weird animated video will play that nobody really cares about (unless they bring back the old Mac vs PC guys, I loved them)
Tim Cook walks up with a smug face and welcomes everyone, talks about how many people came to WWDC this year and how successful WWDC has been. He'll also talk about Retail and the App Stores.
Schiller will come up and talk about the Mac
Schiller will show a picture of the new Mac, list specs and price
Creg will come up and talk about OS X
Creg will do some dramatic intro of like "And today, we're bringing you the next big innovation to Mac OS X... OS X Hollywood"
Creg will spend 30 minutes talking about OS X's new features
Schiller will come back up and talk about iOS
Schiller will diss another company again with another "my ass" joke
Schiller will announce iOS 8 and give a glimpse of the iWatch - nothing more than a glimpse, just like the Mac Pro last year
Creg will come up and talk about iCloud *yawn*
Tim Cook will come up and "So, to recap. iOS 8, some grooouundbreaking new stuff. Mac OS X. Innovative new technologies. New MacBook Airs."
Tim Cook will bring up Elton John or some other music person that no one really cares about.
Curtain.
I'm actually hoping they follow the rules of math and instead of OS X 10.10, they go with OS XI 11.0 or something. Because that'd be awesome. They'll have to get out of 'X' at some point. (20 years from now, OS X 28.0: Now with Launchpad 2.0: Turns your Mac into a rocket ship!)
Creg? You mean Craig, I'm assuming?
And there's nothing mathematically wrong with OS X 10.10 (although it is a mouthful with lots of "ten's"). Software version naming is not linked to mathematics..