A Hokage must be a Strong and Respected ninja.
In your storyline, Kakashiand Tsunade has fallen, and Naruto decline the title of Kage, so who's the new Hokage???
Since you didn't gave any feedback onto other characters, I would choose primarily Sasuke, if he turns to Konoha side or if he doesn't die off course, he's a Strong and Powerfull ninja, he possess the EMS, Sasunoo and Amaterasu, he's well known in the ninja World, and he was named after the 3º Hokage father that was renowned as a great ninja.
If Sasuke couldn't be Hokage, I only see one ninja becoming the next Hokage.
That man is Hiashi Hyūga.
I know he's not the most Powerful ninja e Konoha, but he's the leader of one of the most Powerful and Acknowledged clan's in Naruto World, the Hyūga clan.
And Like I said, the Hokage must be, Powerful, but also Respected and Known, and has the leader of Hyūga clan, Hiashi possess this 3 features.
As for Shikaku Nara we know he's extremely smart, but he don't know how powerful he his in battle. And as for acknowledged in the Naruto World, well, you can see in the Manga, that Raikage didn't fully know Shikaku true value, so, we must assume he's not very well known in the ninja world.