I'm pretty sure they were talking about Wilfred. It explains so much more about how the Doctor acted. He knew if he switched places with Wilfred, he was securing the fact that he was about to regenerate. He confuses poor Wilfred, and even though I never doubt that he'll end up making sure Wilfred gets out safe and sound and back to Donna, the Doctor thinks about all the things he could still do. All of time and space waiting to be seen, to be witnessed. But he hears those four knocks and he answers.
And let me just say how much I love that the last two people he sees are his bestie, and Rose. He just looks so very happy to see Rose one last time, smiling and happy. I don't always ship, but when I do, I ship Rose and Ten.
While I'm sad I won't see Ten again till the next time I re watch all the Who seasons, I'm super happy, because my favorite episode is coming up. Van Gogh was my favorite artist before the Doctor, and Vincent and the Doctor just confirmed and re-established that favoritism by over nine thousand. Plus I love Amy.
And, more episodes with the weeping angels!! They're my favorite baddies. Which is weird, cause mannequins freak me out, and now angel statues freak every one else out, but I love them. Seriously, I want to get a weeping angel statue, put it behind a tree somewhere on campus, and move it bit by bit every so often. See how long till people notice.
On another note: I am about to start reading the Deathly Hallows. I need to prepare myself for feels concerning Tonks, Fred, Remus, and Moody. Not to mention the feels for everyone they left behind. Especially George. He was so young, and his twin is gone from him. He'll never have another Fred :( ROWLING, WHY YOU KILL THREE OUT OF FOUR OF MY FAVORITES. Though if we bump Oliver Wood, Seamus Finnegan, and Luna Lovegood up, the average gets a bit better. It's still sad, though.