My overall assumption of what is about to take place is that obito goes to save rin and in the process his sharingan awakens. Kakashi meanwhile goes off to take out the bridge and arrives at obito having sacrificed his life to save rin but in the process proving his own strength. Then I expect rin to transplant obito's eye to Kakashi with her last bit of chakra before dying making the eye significant of both there lives.

Kakashi could also attempt to take the bridge and fail initially and in the process he loses a eye and retreates at which point he goes after obito. Generally I'm assuming in him gaining the eye and perfecting the chidori by gaining it that Kakashi will in turn be able to finish the mission but will lose everyone he cares about doing it.