"Something just hit me. So in Torchwood when they blew jack up he grew back out of what they found. Well, when the headless monks cut his head off his head survives and becomes the face of boe which eventually dies, but Jack can’t die bc of Rose which means, that from the rest of his body a new head grew and there has to be another jack out there….." - angel-in-the-blue-box via Tumblr
Can I just point out the Face of Boe can't (logically) be Jack? FoB's eyes are greenish. Jack's are blue. FoB doesn't flirt with the *cat lady nurse nuns*. Jack totally would, it's his *thing*. FoB dies. And stays dead. Jack doesn't stay dead. Ergo, Jack cannot be the Face of Boe.