Lol at people thinking the leak was fake. It's not, and im pretty sure Sakurai knew about the leaks.
He probably wants still to be surprises, so he and his team made this video in secret, while telling others (Monolith) it was going to be shulk.
Then surprise.
Same with the leak saying it was Chrom, but the trailer faking out the ending, he is obviously not going to take out a character becuase of leaks, but that doesnt stop him from trolling, and thats exactly what he did.
Would be not surprised if Shulk is the last newcomer to be revealed.
And we already know the leaker doesnt know every newcomer, just a few. He is probably working in translation.