That's not textual evidence that Lyanna left willingly at all. That Ned is critical of Robert's promiscuity is not evidence of his tacit approval of the events surrounding Lyanna and Rhaegar. Ned is an honourable man. He dislikes Robert's lingering hatred of a dead man and he considers the killing of Rhaegar's children to have been a horrible thing committed by horrible people. That is not evidence that Lyanna left willingly or was abducted either way. When Ned is thinking of the events, Martin writes "It was said that Rhaegar had named that place the tower of joy, but for Ned it was a bitter memory". The entire war is a sad memory for Ned where he lost friends and family and cruel acts were committed but that's more evidence that Ned has survivor's guilt or PTSD than anything else. When I think of prophetic dreams in ASOIAF and the surrounding works, I think of Daeron Targaryen in The Hedge Knight. Daeron dreamed that a dragon would die and fall upon Dunk and feared that he was dreaming about himself being killed by Dunk and so he blamed Dunk for certain events that would have ended up with Dunk possibly being killed. Instead it led to Prince Baelor dying in Dunk's arms after Baelor stepped up to defend Dunk. A dragon died in Dunk's arms but it wasn't Daeron but perhaps the most honourable knight in Westeros and a future King who would have brought stability and peace all thanks, in many ways, to Daeron being a fool who acted on his dreams. I'm of the opinion that almost everyone in ASOIAF who claim to have prophetic dreams or are told prophecies and decide to act upon them are idiots. Events never turn out how they expect them and the dreams are vague and often only come close to coming true because the fools who believe them act upon those beliefs to the detriment of those around them. I don't disagree that Jon being raised in Essos similarly to (f)Aegon could potentially be an interesting story. It would have to be a reasonable scenario, however. Likely the Daynes would remember the Peakes, the Coles, the Stricklands, the Butterwells and other noble houses that supported Targaryen bastards over the established rulers. They either had their wealth stripped of them, their lands seized, were forced into exile or a combination of all three. It's extremely unlikely that the Tyrells would risk this. If Mace switched sides after bending the knee to Robert then he would have just as bad a reputation as Walder Frey and it's likely that half his bannermen would betray him in the hope of being raised up by Robert. The BLAST alliance simply outguns the Reach and all the Lords of the Reach know it. The alliance is built on the marriages of Jon Arryn to Lysa and Ned to Catelyn. In such a situation it's likely that Robert would also marry Cersei. The alliance isn't fickle it's based on the feudal traditions of marriages and intertwining families and although Ned wouldn't want his nephew being killed, he also wouldn't want his best friend, his mentor and his wife's family being killed. It'd be a hard dilemma for sure but overall I really don't think that anyone could muster the forces to defeat the alliances formed around Robert even without the Northern forces. If the Tyrells or the Martells took the stupid decision to continue a war they had lost, they'd have Yronwoods and Florents and Fossoways up to their ears.