Masa you're missing an important item in your list: Tobi / Uchiha Madara.

I see Roots, Kabutoro and Tobi / Uchiha Madara as the 3 main adversaries after the Akatsuki demise.

I like where you're going with "Tsunade or Naruto, whoever is Hokage" vs Kabutoro.
It would be neat of him to become the residual arch nemesis of Naruto that pops up various times throughout the rest of the story and even beyond Naruto becoming Hokage.