People mistake the Admirals as the Marine's version of the Yonkou Commanders. They're technically not wrong, but at the same time, it's not entirely accurate. What would be more accurate is if all four OG Emperors formed a group with Whitebeard taking charge and the other three having the highest and equal authority under him. There's a massive gap between a Yonkou and their heavy hitters. This is clearly not so with Admirals and Fleet Admirals. There can be a small gap between a Yonkou and ONE of their heavy hitter, but so far, it's mostly been just one guy. If there's two, it's an anomaly like Roger's OP vice-captain and a wild card like Oden, who does NOT parallel Sanji but rather Sanji would "parallel" Gaban.
Another thing. Oda has done nothing to establish or hint at a power level order with Fujitora and Ryokugyu like he has done with Zoro and Sanji's past Grand Line opponents. As far as we're concern, they're equals as much as they are with Kizaru and Aokiji. It's far more likely that Ryokugyu and Fujitora fight each other or rejuvenated Kid and Law gets them. Zoro will get a top tier (two if Benn is top tier and Shiryu kills him), but it's most certainly not an Admiral.
Another thing. Oda has done nothing to establish or hint at a power level order with Fujitora and Ryokugyu like he has done with Zoro and Sanji's past Grand Line opponents. As far as we're concern, they're equals as much as they are with Kizaru and Aokiji. It's far more likely that Ryokugyu and Fujitora fight each other or rejuvenated Kid and Law gets them. Zoro will get a top tier (two if Benn is top tier and Shiryu kills him), but it's most certainly not an Admiral.