I have to say, I don't agree Torchwood has ever been an explicitly hopeful show. There have been some redemption-type arcs, true, but I don't think they've never been presented as a major theme of the show, and they have frequently involved considerable personal loss and sacrifice with little hope of reward or improvement. Certainly I would say the show has never been hopeful on a personal level for any character, with the possible exception of Gwen (and arguably her only hope lies in her life outside Torchwood - the danger and bleakness inherent in the organisation itself has been a constant theme). Even Ianto, as he begins to come to terms with his loss, is hardly hopeful about his future - he's the one who seems most aware of the mortality rate that comes with the job. Time and time again we've seen unhappy endings, no win scenarios, and characters having to make choices where they can't avoid hurting someone. I agree carrying on for as long as we can is a good summation of the show's ethic, but that's not, IMHO, an inherently hopeful stance - that the operatives has a limited shelf life is implied in the very phrase.