Immediately following the aftermath of Daenerys swooping in on the Lannister army atop Drogon and absolutely torching everything in her way, viewers (and Tyrion) were left anxious about the fate of a certain half of an incestuous twin duo. But the one reason Jaime Lannister can't die on Game of Thrones (at least not yet) has more to do with the narrative rather than how much solid gold Lannister armor weighs.
I think I speak for everyone when I say that I was biting my nails right along with Tyrion as he watched from afar as Jaime made the brave and stupid decision to attack Daenerys as she tried to pull the spear out from Drogon's side. "You f*cking idiot," Tyrion whispered, presumably in unison with everyone watching. Of course, Jaime was greeted with a face-full of dragon fire launched by a protective Drogon, which just missed him as Bronn body-slammed Jaime into the nearby lake in the nick of time. The last shot of the episode lingered on Jaime's body as he sank, weighed down by his heavy armor. If this were real life, Jaime would probably drown. But this is a TV show, and I very much doubt the show is finished with Jaime yet. And he's certainly not going to go down by drowning like a chump.
You may have forgotten in all the excitement of Episode 4, but in Episode 3 Jaime and his forces took Highgarden and he killed Lady Olenna Tyrell with a merciful glass of poisoned wine. Olenna, however, got the last word. Immediately after swallowing the glass in one gulp, she told Jaime that she was the one actually responsible for Joffrey's death. "It must have been horrible to watch... as a kingsguard. As a father," she said. "You see, I had never seen the poison work before. Tell Cersei. I want her to know it was me." Cersei is still operating under the impression that her brother Tyrion killed Joffrey. Jaime still has to tell his sister the real story of their son's death, which will hopefully escalate the already growing tension between them and serve as another part of Jaime's redemption process.
As a character, Jaime has been on the upward swing for so long it's easy to forget that he is the man who pushed little Bran out of the window way back in the first episode of the series. To have his personal narrative cut off before he can see Cersei be his undoing as Lady Olenna predicted would be very disappointing. Shocks and twists are all well and good, but they have to make narrative sense. They should feel earned, as if the story was naturally leading up to it. Ned Stark's death did, the Red Wedding did, and so did Cersei's decision to blow up the sept, killing everyone in it. For Jaime to die so randomly may be true to life, but it just doesn't feel like it's his time. Especially since he still has some very important tea to spill.