Ao has said by Konohamaru as 'The Byakugan Slayer' which mean he is powerful enough to get the title, he is Anbu leader plus his role in shinobi war as head of sensor division not Ino dad. Besides his pall which is Hokage assistance Chojuro, Darui, Kurosutchi now respective Kages in the village. He is probably hokage candidates along with Mei before she is the one selected as Mizukage.
After he said to be retired, Chojuro selected as Mizukage if not it is high possible for him tu run the current Mizukage position. He maybe has been long planned before to be appearance on Boruto project in comeback, maybe there is the meaning for Kishimoto once he introduce to the character long time ago regarding Byakugan how it will related with Boruto.
Fact about Ao, he fought with Shishui and know his chakura, he can see through genjutsu with his eye as proven in Danzo attempt. He stolen or gain byakugan after some clash between konoha ninja in war or mission? Thats all.