Interestingly Tennant will be attending the convention as part of a Doctor Who panel where it is also being suggested a Doctor Who movie will be announced. Such is the popularity and talent of Tennant, that his name has been attached to high profile roles such as The Riddler in the third Christopher Nolan Batman film and that he had also been offered roles in numerous big name forthcoming film projects and that this was the reason he stepped down playing the Doctor. Also an extra tidbit Hobbit producer/screenplay writer Peter Jackson is a huge Doctor Who fan.
Tennant's last episode as the time lord will be shown on Christmas Day in UK, relative new-comer Matt Smith will then assume the role as the 11th incarnation.
UPDATE: Empire spoke to Peter Jackson to see if Bilbo Baggins will be revealed at Comic-Con and sadly we will have to wait a little longer for the answer as he stated 'No, we won’t be announcing Bilbo for a little while'. Empire also got to ask up on what project he'd be interested to do next:
"No, we won’t be announcing Bilbo for a little while," he said when we asked about a Comic-Con announcement. "We’re starting to think about casting, but we’re knee-deep in the script right now. And when we do go to actors, they’re probably going to ask to see a script, so we’re powering ahead with getting the first draft done.”
We also asked him what he's planning to do next after The Lovely Bones, but he's not yet sure. "I haven’t yet decided what I’ll be directing after that. At the moment we’re concentrating on writing a couple of little movies with Guillermo [Del Toro]. A couple of small films! (Laughs) And that’s going to take us another few months of writing to do.
"But we are developing a couple of projects which are potentially films that I’d direct for next year. Temeraire is still on the cards. But those are really taking a second place at the moment..."