Ennies Lobby action happened in a time of 1 hour in One Piece time, we have 3 hours of action here and I believe that the war will be longer than people believes and it will be staged in 3 different parts.
-Huge battle in the sea.
-Whitebeard fleet against Ouka Shichibukai
-The end of an era
Something that a lot of people forgot to speculate are the Pacifistas and Vegapunk technology. Did you know that the space battle from science fiction are based in the old naval battles? I won´t be surprised if we see some advanced stuff from Vegapunk in the battle between the 44 Pirate Ships and the 50 Marine Ship.
Being Sentoumaru the captain of the scientific unit I don´t have any doubt that he will appear in the huge battle from the sea and will mark a difference for the marines until Luffy will defeat him.
Luffy won´t be an arm in a storm, he will be like a butterfly that moves its wings in concrete place and makes an huge storm in the other part of the world.