Dang, if David Tennant doesn't help carry the torch, I may punch something.
Matt Smith will be the Doctor to carry the torch. The headcannon they made was that this reincarnation wouldn't be recognized by Donna so her brain wouldn't catch fire and explode.
THAT'S GARBAGE!That's it, we're in a doomed timeline. I just know it.
Honestly why would they do that? It wasn't even a good episode.