The thought I had after watching the final pair of episodes Sunday night was that RTD was quite deliberately putting a stake through the heart of the show by eliminating all three remaining TW personnel -- Ianto dead, Gwen with a baby to be thinking about, Jack leaving the planet in a cloud of angst -- so that no one else can get handed the show and play with his toys (or turn out to run the show much better than he ever did). Moffat created Jack, and he can have the Doctor run across him at some point, but TW is off the table.