Cleganebowl was entirely a fan service. People have been hyped up for it for yeaaaarssss and it caused enough chatter after the episode aired too. Like the audience loved that shit.
But no, I don’t think it’s ever going to happen in the books. A big part of Sandor’s development is learning to let go of his past and find the peace his brother had stolen from him. That’s his biggest fuck you to his family - moving on.
Sansa praying to gentle the anger inside him seems rather indicative to me that the next time they see each other, he’d have controlled that part of him that she doesn’t like so much. It’s why I think it was so imperative for him to be a gravedigger at the Quiet Isles, otherwise I can’t see why GRRM would waste time in giving this character with rage issues an opportunity to resolve them if he was just meant to kill his brother. That rage would be useful then, but the only character Sandor would ever better himself for is Sansa.
And I think once he finds her, he’s never leaving her side again and neither would she want him to. The memory of him makes her feel safe and gives her comfort, imagine what his presence could offer her. He’s her rock and she’s a balm to his soul. They need each other.
As far as the endgame goes, I don’t see Sansa becoming Queen in the North because I think Bran’s set to be the King. But I still see her holding an important position, potentially as the Lady of the Vale which may come under Northern rule since Robin isn’t going to survive TWOW clearly. Sansa doesn’t want to be queen anymore, but she does want her own home and a family. If she marries Sandor, which I think she will, then she doesn’t stop being a Stark and their children become Starks too.
It’s an ideal ending for book!Sansa, who wants a man who appreciates her for who she is and loves her beyond her name and her title. She’d have the agency that was robbed from her to marry whoever she liked, and she’d choose this rough man who melts around her and who’d never let anything happen to her and all the prissy lords are going to be shook because they all had plans to keep Sansa for themselves.
Sandor loves everything about her that the world considers weakness, and he’d want to preserve that innocence that she fears has been stolen. He doesn’t care about power and politics and would never try and manipulate her or take the power and influence she wields as his own and he’d stare down any fool that came to her thinking they could weasel out some favour they didn’t deserve.
And if she wanted to leave everything behind and go live in some cabin in the woods, he’d be so down for that. And if she wanted to be in this castle in the sky surrounded by silks and luxury, then he’d be there to guard her from any nightmares too. There are just so many ways I can see them ending their story, but in every version, they’ve found happiness and balance in each other. Oof, and a family. There’s definitely a family in every ending too.