I agree that it was time for Obito to die, as for Naruto forgiving him, I believe once it came to light that everything about Obito's past was manipulated by Madara (Including Rin's death), it became that much easier to forgive him. After all, he was just a pawn in someone else's grand scheme.
Not to mention forgiveness is, well, Naruto's thing (and apparently, the whole purpose of the series). So one must wonder, will he forgive Katsuya? Black Zetsu?
As for the shadow in the back, it can only be Sakura.