"Attack on Titan" season 2 still has no specific release date. However, it seems that the speculations are now coming in on what can be expected from the storyline.
Movie News Guide reports that an impending death may be occurring soon that involves none other than Captain Levi Ackerman. The reason for his death, though, may be more of heroic than tragic. After the last chapter, many feel that it's simply a prequel to the imminent storm. Theories state that Levi's death will be triggered by his intense desire to protect the Shiganshina Trio, which comprises Eren Yeager, Mikasa Ackerman, and Armin Arlert. Caring so much for the trio might also lead Levi to make an ultimate choice between them and his fellow Survey Corps Erwin Smith.
Another assumption is that Erwin would be the one meeting his demise after the death flag was raised over his head since execution. However, it is said that Erwin will take on the responsibility of injecting the serum in his arm that will ultimately transform him into a Titan. If this does happen, there is possibility that will eat Eren to try and acquire his Coordinate — the power allowing the user to control the Titans. This will yield him as the next free-willed King.
According to Crossmap, there are two story arcs for the season confirmed for now. First would follow the story of the 104th Trainees Squad facing off the Titans after they have penetrated the Wall Rose. An uprising to overthrow the fake king will also occur, led by Erwin.
Another story arc will reveal the true identity of lover Ymir and Krista Lenz, this will be quite similar to a "Clash of Titans" story. Ymir came back to her human form, 60 years later after eating Marcel. Aside from these, other spoilers include the introduction of the Beast Titan, which would be the biggest among all the Titans. It is also expected that Bertolt Hoover and Reiner Braun will finally be revealed as Colossal Titan and Armored Titan.