The admirals are basically the WG Yonko. I don't see them stopping any Yonko after what Luffy did to Kizaru, granted he was somewhat emotionally compromised, he did have moments of seriously trying to beat Luffy. Especially with Saturn.
I think the Admirals will end up fighting against Yonko in the war but getting tied up with first mates, especially for Luffy.
I am most interested in who Dragon will end up fighting. Sakazuki is pretty fitting, especially since it has been revealed that Dragon was a Marine, he must have some history with Sakazuki... but by the same token so does Luffy, Luffy needs a win over him.
How the hell is Oda going to write this war!?! There are so many moving parts!
I know he is going to pull it off, and it will be the biggest war in Manga/Anime history.