Scott Snyder has said that when the Joker returns he will have a new face and a new form. What do you think that might be? And what kind of explanation will he give?
I don't know about the face and form. I could see him going in any number of ways. As far as the explanation, I expect he will be deliberately very ambivalent and playing off the end of DOTF. That is, I expect, especially if the face and form really are noticeably different, that he will leave open the possibility that the Joker actually died at the end of DOTF and has been resurrected, thus fulfilling Bruce's dark musings about Gotham sending him back worse than before. Snyder won't come out and say that, but it may well be implied all over the place.
Such would fit not only with DOTF, but with Tec 27 and its implications that the Joker is, in fact, immortal, or at least the avatar of some immortal principal of Gotham. It would also fit with Snyder's statement that the Joker's first appearance was about love, and the second will be about hatred. That is, under Joker's anger at having been spurned by his "King" will be the implied lament "You killed me!"