Based on the trailer, I'm guessing Waltz is Blofeld and Bond's brother. That makes him a bit more interesting and its shows the great divide in the Bond brothers. One became a hero and one a terrorist. It would be ironic for Bond' biggest nemesis to just be his brother. It also makes it harder for him to just kill Blofeld as he's his only remaining family. Definitely a nice little twist to the mythology, if correct.
Ehhh I dunno. I think that'd be a bit silly.