I've got to say, I don't think the supernovas will all be just captains of their crew, here's some thories on where the supernovas ended up
Luffy, Kidd, Law have distinct crews they would appear to be rivals with each other and my guess is these 3 will always be there own leaders
zoro and killer = alawys first mates
X. Drake = It was pretty clear to me that X. Dake couldn't have survived two years as a rookie with a Yonkou hunting him down, he wanted his attention but my guess is he wanted it so that he could join him, my guess is he's up in Kaidou's big 3 and him and zoro will have a nice showdown someday
Bonney = she clearly needs protection, Black Beard made it obvious that she's to weak my guess is based off the picture she's escaped and become a revolutionary, plus it seems she has a vendetta against the WG they'd be the perfect group for her
those are the ones I feel pretty solid on here's where it gets tricky
My belief is that capone and apoo (along with bonney) aren't as much high tier fighters as they are awesome df fruits and apoo seems to be a rival for brook and is from a weird tribe, that are a minority Big Mom seems to love people of minorities (long leg tribe, animal people, cyclops, jinbei and his crew as an ally and whatever thehell bobbin is)
so Apoo = Big Mom's crew, for the above reasons
Capone = I have no idea figure that out yourselves, but I could see a guy with hundreds of followers who you can't see before they appear as a good match up for our old I have hundreds of followers usopp
Hawkings and Urouge = besides Buggy possibly not accepting his shichibukai invitation it seems there's two open Shichibukai seats, I doubt there just gonna put out some nobody we as readers haven't heard of when we have 9 powerful guys here (who aren't main characters) who were supposed to affect the new world during two years and so from my point of view (which you may disagree with) since kidd and law are two guys who seem to always be luffy's rivals and killer is with kidd, and capone and apoo seem to have two rivals of the SH's who I doubt will ever be shichibukai material, and bonney is to weak and Drake is in for Kiadou my guess is two guys who really showboated there power Hawkings and Urouge (who fit the extremely tall standard also) would fit well in the seats of shichibukai
and for those of you who will say urouge is weak compared to the other supernovas (cause I've seen it before) the hell are you talking about! don't get caught up on bounties the guy did what it Took the whole monster trio to do send the thing flying! with a couple punches his strength may have been greater then gear 2 luffy back in the day
let the arguing commence
EDIT: oh yeah how about this guys, He couldn't fit zoro in the picture!!!!! why all the killer theories fucking stupid if you ask me, just because zoro's not in the picture, did oda say it was supernova captains or supernovas?