Now that "Doctor Who" fans know for sure that there was a Doctor between Paul McGann and Christopher Eccleston, that shifts the numbers. Now Peter Capaldi will technically be the 13th Doctor, rather than the 12th. That means this will be the 12th regeneration for the Doctor, which is all he has to his life.
Steven Moffat had said time and and again that the Doctor only has 12 regenerations, but that "there's something you're all missing." He says at some point in the history of "Doctor Who" there was an event that explained how the Doctor will continue to regenerate.
This was before "The Day of the Doctor," so it's not likely that he was talking about about the War Doctor taking up a slot. However, how many regenerations are actually left? With the show at the height of its popularity, ending whenever Capaldi decides to throw in the towel isn't a possibility. Still, at some point Moffat is going to need to clarify his remark because as dedicated as Whovians are, the supposed loophole has yet to be discovered.
With the inclusion of the War Doctor, things have only gotten more complicated. At least before there was an opening for a Doctor after Capaldi, giving Moffat time to work out a proper reason why the Doctor will continue.
After "The Day of the Doctor," it's also clear now that there might be more than 13 known Doctors already. There have been some gaps in "Who" history, and you never know how many Doctors came and went during that time.
In the end, fans don't need to figure out if Capaldi will be the last Doctor, it's obvious that he won't. It's time for the think tank to get together, scour over every little bit of "Doctor Who" and finally solve the regeneration loophole mystery. Your Doctor needs you.
Photo/Video credit: BBC America