Does anyone else theorize Jon will have a relationship with “Alayne” specifically, before Sansa? Thinking of where ASOIAF leaves off and assuming the general thread of the tv series is based in GRRM’s plans for TWOW & ADOS, I assume Jon & Sansa will still be the first Starks to be reunited, Jon will still win the Battle of the Bastards thanks to Sansa bringing the force of the Vale and Jon & Sansa will rule for at least some time together. I was trying to think of how the differences in storylines could be reconciled. Here is a potential theory to line these storylines up: -After learning of Jon’s death, Jeyne could end up turning back from Castle Black for the Vale either escaping feeling “Arya” will not be safe if Jon has been killed and that she does not have other options, knowing Baelish knows the truth and might know what to do. Or sent there by Stannis since her only other known alive family is there. - After Jon is resurrected he could learn that “Arya” was there and headed to the Vale, and now free of oaths, go after her. -There Jon could be united with Alayne and enter a relationship with her, either arranged to unite the North and the Vale in return for their forces, or thinking they are both bastards and aligned in status. Depends on how Alayne’s storyline has progressed, for example if she has married Harry and now Harry and Robin have both died. He could also simply fall in love with her. Or some combination of the above. -Another potential theory I’ve seen regarding Jon’s resurrection is that he may have gaps in his memory in the immediate aftermath, he might not recognize that Jeyne is not Arya right away, confused that he does recognize her from childhood. He may feel Alayne is familiar but not make the connection it is Sansa -In my opinion, this would lead to the same outcome of Sansa bringing the Knights of the Vale to fight for Jon in the Battle of the Bastards. And to the same outcome of Jon & Sansa ruling Winterfell together as Lord and Lady, and then the North as King and Queen but perhaps as Jon & Alayne, at least initially. - This resolves some discrepancies to me- why is Sansa not even considered as alternative to Jon when she is a true born Stark, when women rule in the North elsewhere? Do the Knights of the Vale really only come because Sansa asked Petyr nicely and he finds a way, or because the Lady of the Vale requested? Also side steps the concerns they might have about a public view of their relationship before they know of Jon’s true ancestry. -And of course Jon & Alayne ruling as King and Queen in the North parallels best with Jaeherys and Alyssane ruling as brother and sister and King and Queen.
I must admit that I have two problems with this theory: For Jon/Alayne to work, it is not only Jon who should have memory issues, but both of them. Otherwise a union is impossible. If you look at the marriages in the North, there has never been any wedding that was closer than 4th degree (according to Roman Law), the closest we have is cousin marriage and half-uncle-niece (which is 4th degree). There is no way that a union without the parentage reveal would be possible for Jon and Sansa. And Alayne remembers to be Sansa, even if Jon forgets everything, Sansa probably doesn't. And she wouldn't marry the man she knows to be her half-brother.
The other thing is: I really think we'll get Sansa as the Girl in Grey. There are so hints that point towards that: a subversion of the Red Riding Hood tale (Sansa being rescued by a wolf), Sansa reiterates Eddard's path North when he claimed the North in Robert's Rebellion, the rule of three (two false "girls in Grey", one true), Sansa singing Jon back to life, etc.
I freely admit though, that I have only a very vague idea how this will play out in the books other than that I'm sure we'll get a plausible reason for why the Knights of the Vale will ride for Sansa.
As for Jon and Sansa ruling jointly pre-parentage reveal. I could imagine something like they did on the show: Sansa as Lady of Winterfell, inheriting the seat that is hers by right as the last (known) trueborn child of Eddard Stark and Jon as king whose task is the military defence of the North against the threats that loom on the horizon.
That is not to say that a Jon/Alayne scenario as you set it up is not possible. I just think that we have good reasons to think that Jon will have memory issues (we have seen it with Cat and Berric) but there is no reason to think that Sansa will forget who she is. And if she does not remember who she is, she has no claim to the North and thus no reason for a joint rule with Jon.
I hope I haven't completely misunderstood your reasoning. If so, please feel free to correct me.