I love the books.. Heck, I even wrote a continuation of the sixth one - started it a year ago and it's still going
Over 65,000 words now
Anyway, that aside - I honestly do not know what will happen. My guess is that she will kill Harry off, as that way she will not be pestered to write another book about what happened after the death of Voldemort - however, if she does kill Harry off, then she will get a LOT of angry readers at her doorstep. Heck, I may even join if the fun if that happens! She's in a lose-lose situation
The books are far too complicated and open-ended to predict what will happen in the seventh book - if you want to see some good theories, go to hpana.com. They have a forum there to discuss just that.
Another problem is that there is a lot of FUD. Some people even say that Harry is a horcrux - this I highly doubt. Then there is the locket Harry found in the Order of the Phoenix's HQ (Black's old house), which might have been one of Voldemort's horcruxes - but wouldn't Harry have noticed the 'evil' coming from it? And how would it have got there in the first place?
While it may be a nice bedtime story, it certainly isn't a book for kids if they want to fully understand what is going on
I'm going to have to read the whole series again (excluding the seventh, which, of course, isn't out yet) to try to put together a few reasonable arguments!
Whether she kills Harry or not... She's going to be in trouble
One other thing I've always wondered about... Do you think she has written all the books already, and is just delaying the release of each one to make the greatest amount of money out of each one? Or, do you think that she really is writing the seventh at the moment, and releases each book a few days (or a couple of weeks) after she completes them?