Eiichiro Oda has made an unexpected announcement at the Jump Festa 2018 which has made every One Piece fan thrilled. The author teases by announcing a One Piece Legend who is going to be the Straw hats greatest enemy. He also hints the legend's connection with Whitebeard.
"By the way, One Piece will finally enter Wano next year!! (cheer!!). Some well-informed audience might think, "You said the same thing last year right?" Yes I did say that, because I thought OP would be able to enter Wano in 2017. This time I should like to add new information"
"I'll introduce one of the legends who lurks in One Piece world. The greatest enemy ever for Straw hats will hinder their way. Perhaps it will be something related to Whitebeard. Oops, it seems I'm being too talkative. Can you believe Marineford summit War will look cute compared to that".
The most obvious candidate is Kaido, but the context of the message focuses on the introduction of a new character. From this, we can conclude that this character is yet to be revealed. Some think it's admiral Ryokygyu (Green Bull), some believe it's Shiki Gol D Roger arch rival. Whoever it is, the person is going to play a massive part in next year One Piece story line.
These events will make Marine ford arc look like cute is something Oda has hinted in the past when talking about the final One Piece war.
"Any way there are tons of stuff that I wanna draw next year as well. I'll keep moving forward with my full force!! I'm sure you are gonna LOVE it!!".
The manga is already going through a very tense Whole Cake Island Arc where Straw hats are facing the heat of Yonko Big Mom. It will be very exciting to see how they will find their way out of Whole Cake Island and reach Wano.
Source: Sandman Twitter