Itachi and sasuke can win this
lets bear in mind that sasuke is more powerful now than he was when he fought the kages. also he hasnt just finished defeating danzo so he's super energetic.....
A- his fighting style is close range based and itachi,being so skillful, can put him in a genjutsu before he can actually attack.
Tsunade- she's still alive now cuz of her ability to heal, but shes not that fast. with sasukes sword moves and raiton, he can use the jutsu he used to cut Diedaras birds wing to cut her head off while shes charging
Mei- suiton loses to raiton(sasuke) 4 out of 5
Gaara- sasuke could just use amaterasu on the sand when its protecting gaara from itachis move to create an oven and when she lets her guard down itachi can finish him off
Onoki- he would be their greatest challenge but they would be able to pull it off, seeing how sasuke got rid of the zetsus without even moving
Lets also bear in mind the move the brothers did when fighting with kabuto(also the giant pig) with their susanos
Bottomline: the brothers might be able to win. but am not saying the kages are completely out