Stuff like this is why I’m actually kind of hoping Jon dies heroically in ADOS just to prevent the last book turning into the extended edition of Return of the King all over again.
Something that may or may not be deliberately clever: in the situation Robb thought he was in when he made out his will, Robb’s actual parentage would… still have made him Robb’s closest male heir. With the other male Starks (supposedly) dead and the only known surviving woman politically unpalatable, the son of Robb’s father’s sister (his cousin) who has the Stark look and is a respected member of a venerable northern institution would absolutely be a top pick.
People focus on the Rhaegar connection a lot, but the Lyanna connection is just as important.
However, from a practical standpoint… Robb’s will is going to swing a big bat with the northern lords, but that will was written when it was thought the other Starklings were dead. If Jon doesn’t want to be Lord of Winterfell (and honestly I’ll think less of him if he does, because he swore an oath to the Night’s Watch) there’d be no problem at all passing that cup to Bran or Rickon.
That’s a good point.