The way in which they eviscerated OOTP, I have to admit I am a bit surprised as well that they're dramatizing this moment, and I find it encouraging. Because it's a HUGE set up for properly finishing out Snape's entire character. That in 6 it looks iron clad like Snape is bad because of this, but in Joe's great way thanks to the writing, it'll pay off in 7 how he was able to commit to this, and yet still maintain his overall loyalty position to Dumbledore.

I just hope it goes a bit further, and it's an indication that Bellatrix's & Snape's conversation taking place prior to the vow will be included, when Snape very calmly gives her the answer to each and every one of her questions doubting him. But I wouldn't be surprised if that's not there, it's very dialogue heavy, of course. It's one of my very favorite parts of the book.

But at least as far as the first act of the story, we already know that Dumbledore picking up Harry from Privet Dr and chatting with Uncle Vernon is in, as well as Harry and Dumbledore going to Slughorn's house to recruit him.
Of the first few chapters, the one I can see most easily not being included is Fudge and Scrimger meeting with Britain's regular Prime Minister, there's no way that's making it in.