Oh yeah, I totally didn't see it coming that all of the Malfoys would survive! But at the same time, it did make sense to me: the most important thing to the Malfoys is their family and how special it is. If anyone threatens that, whether it be this perceived "mudblood infestation" or Voldemort himself, they're not going to take any crap for it. Especially since they set up Narcissa as asking for the Unbreakable Vow to protect Draco in the sixth book, I was able to buy her betraying Voldy at the end of this one. Also, the fact that Draco seemed unwilling to identify Harry, Hermione and Ron in the Malfoy Manor seemed pretty telling.