Like I say, I don't think Donna's dead yet. I'll even go as far as to say I'll bet she finishes the season. My concern isn't that Moffat will get rid of her, but that the writing's on the wall for her to be gone by the end of S4 ... or midway through the hiatus year, at the latest. If so, I'll be unhappy about it! :)

Heck, if you watch the trailer, alt!Donna is coming from Pete's Universe. Which will be very, very interesting...