Shin? Good luck. Ain't no Hunter but Crow qualified. Even if anyone steps up to the position, of which no one has, they'd not be respected.
No Hunter wants to be Vanguard so the Dare was created to anchor one to the job. When Ikora informed the top Hunters she wanted to discuss which one of them should take the position, they decided to instead take everything they own and flee the City before the meeting took place.
Every Hunter but Crow knows Crow is it. Either Crow knows and thinks he doesn't deserve the role or he doesn't.
Shiro is the most logical choice. Caydes right hand man and proven field commander.
Crow has no leadership experience, no mentoring skills and has proven to not put the City first in his decisions.
He’s about as unqualified as it gets.