Supernatural

Co-showrunner Andrew Dabb revealed that COVID meant the writers had to rework the final two episodes of the series. Dabb said: 

Dean was always going to end up in Heaven, and we were always going to see Sam's life in fast-forward, but those final moments were supposed to take place somewhere else. When Bob Singer and I sat down to talk about season 15, and our inevitable end, we came up with something that felt like a fitting version of Sam and Dean's Heaven: all the people the boys had met along the way (or, at least, those we could convince to fly to Vancouver) crowded into a re-built Roadhouse, as the band Kansas played our (official unofficial) theme song: 'Carry on Wayward Son.'

Meanwhile, on the Supernatural Then and Now podcast, original show creator Eric Kripke revealed his original plan for the show, if it had ended after five seasons as he'd originally envisioned:  

There was never any plan for Dean to jump into hell with him. I actually ultimately think it's good they didn't leave the ending to me because the ending that I had in mind was way more with like a horror movie DNA which I think would have been unsatisfying. So the scoop is, now enough time has passed I will tell you what it is. I don't know if I've ever even said it publicly. So the way ending was supposed to go is Sam goes into hell, Dean works his ass off to try and get him out in montage similar to what is there but ultimately can't because Dean’s big emotional movement was that he had to learn to let go of his brother. Now the fact his brother is being tortured in hell. When we came up with it we weren't quite so specific.. we didn't have like. remember we had Dean in that Hellraiser chain world. And so I think it was probably like more like oh where did he go but I'm gonna let him go. Dean goes back to Cindy [Lisa] so he does back to Cindy and they have a baby and its a girl they name the baby Samantha and then the final image would be like he's got Samantha, he kisses Samantha and he kisses you know Cindy and puts the baby in the crib and they leave and turn out the light and then a dark figure comes over the crib and it goes back to the teaser of Supernatural and then it's like a hard blackout and theres a strong implication that it's all gonna start all over again and so Dean is gonna become John and Samantha is gonna be the new demon hunter and his wife is gonna be on the ceiling and Sam is obviously gonna get back into.. it meant to end with a big question marks. Oh This story is going to continue. Its one thing I always loved about the Buffy ending which It was more hopeful than this. After they got rid of the Hellmouth, they were like oh there's a whole bunch of other Hellmouths. What are we gonna go?. You push in on Buffy and you just know the fights gonna continue. I was trying to give it my horror movie spin on that. So that was the ending. It was alot of question marks. Not a happy ending. That horror movie ending.