Anyone who sits on the Iron Throne automatically has a huge target on their back. Add to that the fact that Cersei is one of the most hated figures in Westeros, just murdered a bunch of people and has no actual claim to the throne, and you can bet she probably isn't long for this world.
While not included in Game of Thrones, Cersei's death was actually prophesied in the books, where Maggy the Frog told her that after her three children died, the "valonqar" (High Valyrian for little brother) would choke her to death. Will Jaime have to put down his sister just like he did the Mad King? Many fans are betting on it.
A lot has been made over how Cersei and Jaime "came into this world together," so wouldn't it make sense if they also left together? If Jaime is forced to kill Cersei once she goes full Mad Queen, he may not want to face being both a kingslayer and queenslayer. There's a small chance Jaime will choose to take the easy way out and kill himself once the deed is done.
Whenever a character seems poised for redemption, it's accompanied by a sense of dread. Theon is trying so hard to do right by Yara and be a good person, that we can only assume his noble deeds will get him killed. That just seems to be the way of the world in Game of Thrones, and Theon is heading to war right now...
It would be amazing to see Yara become the Iron Island's first queen, but everyone who heads into battle alongside Daenerys is at risk. If Yara is killed while fighting for the Dragon Queen (and thus, the Ironborn's independence), that would force Theon to rise to the challenge of being king - something we wouldn't put past the Game of Thrones producers.
There aren't a lot of villains left on Game of Thrones, and Euron is a very expendable one. He'll probably put up a bit of a fight, but we have no doubt Daenerys will follow through on her promise to help Yara and Theon slay their uncle.
As Melisandre told Jon, she's ready to die (which makes complete sense since she's old af). And the Red Priestess may now be leading herself directly to death's door. After being exiled from the North, Melisandre is riding towards the Riverlands where Arya is lurking about, ready to check names off her list. Melisandre got herself added to the kill list in Season 3, when she bought Gendry off the Brotherhood Without Banners, so she better watch out if she runs into Arya during her travels.
It's been a while since we lost a Stark (and no, Rickon doesn't count). Sadly, our money is on Sansa to go next. After Jon was crowned King in the North, Sansa gave Littlefinger a look that's full of regret. But if she does decide to side with Littlefinger over Jon, she's probably in major trouble. Not only because Littlefinger is the least trustworthy guy in Westeros, but also Sansa is not the Stark with a big legendary destiny. Jon is almost definitely the Prince Who Was Promised and anyone who goes against him before he can fulfill the prophecy likely won't fare well.
Brienne is too good for this world. Straight up. And as we saw with Ned, being good and honorable gets you nowhere in Westeros. We only ask that the person who kills her is anyone but Jaime. That would just be rubbing salt in the wound.
If we were the Brotherhood Without Banners, we would hightail it North ASAP. As of now, they're in the Riverlands possibly not to far from Arya Stark, who would love nothing more than to check Beric and Thoros' names off of her list.
Arya admitted to the Waif that she had taken the Hound off of her list because she was conflicted over whether she still wanted him dead. If Arya and the Hound run into each other in the Riverlands, it could create a huge turning point for Arya. Would her remaining humanity spare his life or is Arya too far gone to do anything but kill him? We'll have to wait and see!
The Mountain has got to go. But will it be Arya, who has him on her list for the torture at Harenhal? Will it be the Hound, whose long-standing feud with his brother could only end one way? Will it be Ellaria or a Sand Snake, who could finally get their revenge for Elia's murder? If we had to choose, we'd be rooting for the Hound to kill him, because even though it wouldn't technically be Cleganebowl, we'd love to see the brothers duke it out to the death.
Littlefinger can't see the forest through the trees. He's so focused on claiming the Iron Throne, he's oblivious to the fact that there may not be a kingdom to rule once the Night's King reaches Westeros. That's the kind of mistake that could get a man killed. And boy, does he have it coming!
Littlefinger has done so many horrible things over the years (particularly to the Starks), we'd love to see Sansa turn on her mentor and take him down. If that does happen, we're betting Littlefinger has his own Severus Snape-style "Always" moment, but instead of romantic, it will just be super creepy. We can't wait.
Every battle has its casualties, and we're sure Daenerys' attack on Westeros will be no different. If any of her inner-circle is going to die in the upcoming war, we're betting it'll be Greyworm. He'll presumably be the only one out there on the battlefield, and as much as it hurts us to say this, Greyworm won't really have a purpose in the show once the battle is over.
Jorah has a fatal disease with no known cure. But even if he miraculously discovers a cure for his greyscale, we still would be worried about him. Jorah would literally do anything for his khaleesi, and how bittersweet would it be if he saved himself from greyscale onto to sacrifice himself to help her shortly after?