After read the chapter 550 I was thinking, I supposed as the majority, that it doesn't matter, Luffy or Whitebeard are going to arrive at time to save Ace, but what if they won't arrive at time? What if Oda planed that they won't arrive? Did anyone think about it?
In favor: It would be a unexpected twist.
Against: Oda didn't kill anyone in the present.
Kinai.