That is silly. They are going to have to split up the books eventually, especially if they keep pushing vital information into "the next movie".
I so desperately hope for Director's cuts of all the movies. I would buy them.
There will be no director's cut. The DVD of book one includes lots of deleted scenes. They are best left deleted.
The script for the current movie was trimmed to its current length before shooting started. The changes were Rowling approved. My source for this is the current issue of Entertainment Weekly.
The script for number four is also finished, and although no one has released the timing, it will be one movie. It will include underwater scenes, because Radcliff has been taking diving lessons.
There will be no attempt in future movies to cover everything in the books, but Rowling will approve of changes and cuts.
It had better not be short; there isn't too much they could get away with cutting out.
And I'm with you on the extended/director's cut idea!!