But he is wrong as we can't offically declare Sabo is dead. The reason I refuse this is because of two reasons.

Oda isn't the type of guy to kill a character instantly and off-screen as we have not seen anything of the sort in the past. Sure, Hiruku died off-screen but we saw him drinking to his death after his speech. We saw him slowly dying for Chopper sake. Even if Oda does killed someone off screen instantly, you have to think about one thing. For what purpose would Oda resurrected Sabo only to killed him again in a few years and have Ace fruit? None. Luffy and his friends already wake up to see Grandline is stronger then they could handle since their captian couldn't do anything to save Ace. Do we need another timeskip since we are so close to the end (in five or four years from now)? No we don't.

Now this is my theory... the World Government feed some lies to Morgan (through his employees) in hope to provoke Dragon into attacking them. I know many would think it is Marineford War again, except what if it's not. Rather than have Luffy go back and joined a war, what if Dragon spies reveal that Sabo was still alive. I think Dragon would turn himself in just to save Sabo.

Think about it, you don't cut one of the snake eye and expect it to die instantly. It can relies on other sense to live for a long while. Instead, you aim for the head and that head is Dragon. Dragon created the revolutionary army, Dragon was the one to challenge the World Government, and it was Dragon that made the Celestial Dragons afraid. We could take this as a chance to learn more about Dragon past and his motivations to start this war (I bet it involves with Luffy mother as many fans believe) against them. The World Government would hopes that this news would discourage anymore rebellion, but Sabo would used this to encourage the world to fight for their freedom which would make him a leader of the Revolutionary Army.

Now I know this is very unlikely to happen, but it's as dragon says. “We must confirm the facts.” Unless we see the body or have someone at least confirm it... We can't rule out Sabo Death just yet.