"We'll truly settle things between us"

[Bad Touch Yakushi]

I'm pretty sure it means to finish the fights they have been having up to this point, a final bout between eternal rivals maybe.

But as said in the opening post that would serve nothing except for their ongoing penis-comparing contest which I would've thought they'd gotten over already

if they fight properly they'll kill each other and what would that achieve

 

[Uzumaki Naruko]

What if they are never going to fight another time, and we view Sasuke's words and him keeping the headband as a silent promise of eternal rivalry/friendship?

 

[Bad Touch Yakushi]

What if they are never going to fight another time, and we view Sasuke's words and him keeping the headband as a silent promise of eternal rivalry/friendship?

equally as good

 

[Uzumaki Naruko]

equally as good

Exactly