Oda is already portraying Kizaru in a right-hand man fashion, fitting a role similar to both villains (Crocodile-Bonez, Lucci-Kaku, Kaido-King) and good guys (Garp-Bogard, Coby-Helmeppo, Smoker-Tashigi, and of course Luffy-Zoro). Kizaru also has a story of pairing with second-to-captains (Rayleigh, Marco, Beckman), almost killed Zoro and belongs to the old trio —so even easier to differentiate him from the newcomers and justify a distinction like that between King and Queen (very close in bounty and depicted as a duo, but with King established above both in strength and unofficial rank).
Considering that Fujitora may easily not be an enemy but fill a Drake-like role plus the fact that Sakazuki was paired with Whitebeard (while other top tiers went to his commanders) and he probably became even stronger after defeating Kuzan and being promoted (so yes, above any other admiral), how could anybody look at this picture and deny the possibility of Luffy versus Sakazuki, Zoro versus Kizaru and Sanji versus Ryokugyu?