Umm... There is one problem and that's oikawa isn't Brazilian so he can't play for their national team. Unless the rules of international sports have changed that won't be possible or oikawa taking Brazilian nationality
I know ugh i just hope so
I thought hes in argentina?
Wait I can't remember that I'll have to read the previous chapters again to confirm
Yes Argentine
So, the perfect scenario is kagehina made it to the national team, get to play together again. Im not saying this just because a mere bromance they've got. Hinata out there, can do really about everything. Dig, serve, quick set, playing decoy, setting the ball... you would have definitely insane to not wanting him play for you country.
And after they went into the national, they would meet oikawa who will win against them.
What so perfect about this is, kagehina can play as a teammate yet playing rival again when they back to their v.league team
As long as i remember, furudate is kind yet cruel at the same time. He made karasuno win against shiratori, inarizaki but lost to kamomedai. He unlock so much of hinata's skill but made him sick outta court. So i think he will give us the best scenario but will eventually punch us at the place we least expect, just be prepare