I really have to give the writers a lot of credit. They obviously have their finger on the pulse of what viewers are going to expect from certain scenes, and manage to throw out all sorts of surprises. The way they shot the scene of Meredith and Derek in the elevator towards the end of the show, I was convinced thatthey were going to jump each other in the elevator. I figured that was the "shocking end" that ABC was promoting. But they just walked off.
Then, we get to the gun shots, and I just somewhat thought "oh well, the jerk boss guy has been shot". When Bailey went outside, I was still thinking that. Then to see Burke laying there? I never expected that!
It's the way they lead viewers down one road, only to take another, that makes me think that Izzie won't be the character out of the intern program. Yes, it's highly unrealistic for her to contine, but we could make a long long list of all the twists this show takes that are unrealistic. They're not exactly striving for medical realism. I think the theory floated earlier that Christina will leave surgery for an ER internship, or even that Alex will leave surgery for a gynecology internship, is more likely. I think that the language they're using for the info is very specific - someone will be leaving the surgical intern program. That doesn't mean they're leaving the hospital. It'd be too hard in a show like this to have a constant character who didn't work at the hospital. Too much of the real storylines take place in the hospital.