For all that they hate Cersei, neither Tyrion nor Sansa are the type to physically kill her or contemplate killing her, which, of that trio you mentioned, leaves Jaime... and, contrary to what many fans think or want to think, his devotion to Cersei has not wavered a single iota thus far on the show, which is why I describe the possibility of him killing her as a "jump the shark" moment.
Man, even after being the last person on the planet who thought Jon Snow wasn't coming back from the dead and not realizing who the Man in Black was on
Westworld, and insultingly shouting down everyone else who had the right answer in both cases, you've still got that whole "I know more than everyone else" thing going on, don't you? It's not that you have your theories and preferences, everyone does that and it's fine, it's the lack of humility and the finality of your predictions, as if they're 100% guaranteed to come true and there's no possibility of you being wrong, when you don't exactly have a great track record in that regard, even when it comes to things that were completely obvious to most fans.
Now, I'm not saying Jaime killing Cersei is completely obvious and a guarantee. Not by a longshot. But saying there's zero chance of it happening is hogwash. The parallels between him being the Kingslayer and killing the Mad King at great personal cost to his honor and standing and possibly having to make the same decision regarding a completely unhinged Cersei at the cost of the love of his life are too juicy to ignore from a tragic and dramatic standpoint. If you missed the worried glances he gave her in last season's finale (and several times this season) when she took the Iron Throne for herself after blowing up the Great Sept (and by extension Tommin's suicide) then you weren't paying attention, because that was specifically meant to invoke Jaime's concern with the Mad King blowing up King's Landing with Wildfire. And before Olenna went full ice queen and confessed to murdering Joffrey, you could see that recognized the truth in her words about how dangerous Cersei was.
Whether or not he will overcome his love and devotion to her if she goes too far is not at all clear-cut, but it's not as out of the realm of possibility as you make it out to be. There's definitely some hesitation in Jaime's eyes and voice when he see what Cersei has become, regardless of what he tells others like Edmure Tully.
Tyrion killed Shae, albeit as much in self-defense as in anger. Tyrion is not the type to kill typically, but he's capable, and Cersei would certainly be at the top of his list of deserving targets. Plus, I did say he might also use paid help like Bronn to do the job.
I could absolutely see Sansa develop into a Lady Ollenna type; smart as a whip, and absolutely ruthless and cunning when it comes to getting what she wants or defending her family. She's the most unlikely candidate for killing Cersei in my mind, but it's again not out of the realm of possibility, and she certainly has motive. Plus, poisoning would be a bit of karmic justice after she was blamed for poisoning Joffrey.
I said he walked through the fire on the ground and extinguished it. I was making a point about how he radiates cold and how that might have played a part in freezing the lake faster.
