If you have a giant pinch of salt handy, read these supposed "spoilers" for DH. (That is, unless you are avoiding spoilers. I find that I am not.) There are a *lot* of 'em, folks, and rather spoilery if true. cmwinters will find at least one directly applicable to one of her theories (should she choose to be "spoiled").
The only one I really care about, of course, is: Snape's role is to be SIGNIFICANT but not LARGE.
To me that says: fan fic heaven! :D But I was planning on that anyway. *eta* Possible spoilers in comments.