"Worthiness" has always been a interesting concept in ASOIAF. What traits we might consider worthy is probably very different to what is it for the average Westeros. Reminds me of Jaime and Brienne's discussion of true knights. Or at Dunk's trial were he begs for a true knight to help him.
I am curious if it is a sword chooses the wielder or if there is the secret Dayne council and you have to pass a trial to gain the sword. So many mysteries of Dayne, it is maddening.
Who is left that would constitute a Dayne council? What exactly is a true knight or how does Arthur Dayne qualify? If he was the last 'worthy' Dayne, how is the next successor judged? Does the sword choose?
So far, the only worthy knight seems to be Brienne.
Who knows?
I don't.
Martin likely does.
Darkstar will be the next Vulture King.
Craster has 19 daughters and there are 19 castles on the Wall, coincidence I think not!