I'm firmly in the Reset Camp, in terms of where I think RTD is going with the story, that history will collapse and the universe will revert to its pre-Time War state. The scene in the bookstore comes, as we know, near the end, along with the scenes with Rose and Jack and Sarah Jane and Luke. Assuming the reset, I suspect that before history collapses and his own past unhappens, the Doctor will travel backward through his own timeline, to say goodbye to people that, ultimately, he will never know. The bookstore may be an indication that he's reached the pre-Time War universe, that history has collapsed and rebooted, and that his own life has now become fiction.[/spoiler]