Pimping: "Toy Story 3"
Why we want him:  He not as spry as he used to be, but Hanks can still light up a room and entertain like the best of them. 
Why he'd do it:  Pixar can't take any chances.  "Toy Story 3" needs to have a monster opening or the company may take it as an embarrassment after the landmark grosses and reception of the first two films (both considered classics).  The company has a long history with Comic-Con and Hanks and Tim Allen (both Sci-Fi fans by the way), could be easily convinced of how family friendly Hall H can be.
Chances: 50%.  We're confident Disney and Pixar will have the filmmakers and a special sneak peek, but it might be a stretch to hope Hanks and Allen make an appearance.