What are you talking about? In the GSC chapter, Suicune initially chose Misty but it joined Crystal at the end. And if I recall correctly (I only read the part where Suicune chose Crystal recently so I only remember that part clearly) Entei was supposed to go with Blaine and Raikou was supposed to go with Lt. Surge but they went with Silver and Gold, respectively, at the end. It's not that hard of a stretch to picture a scenario where Black's Reshiram defeats Zekrom in battle but then Ghetsis arrives with the Kami trio ready to wreak havoc and since N refuses to fight his own adoptive father and since White wants to join the battle Zekrom chooses to follow White's orders.
You do realize that Suicune has always had Crystal on its mind for a long time. It chose Misty because it deemed her worthy to fight alongside it.
Also, as much as White seems to be gaining skills with battling, I doubt that Zekrom will choose her over N in the end.
The reason is because both dragons choose their partner based on whether they will fight for ideals/truth. As far as I can see, White doesn't really show any signs of having specific truths/ideals that she is fighting for.
She already acknowledged Gigi's decision to battle whilst still disagreeing with N's methods.
Even though I doubt she'd get a dragon on her side, she may still have an important role with another Legendary.
EDIT: Also. I don't agree that any Kyurem cloning stuff will occur (that's a really huge *** pull)
However, it would be kind of plausible for Kyurem to absorb both the Dark and Light Stones to be able to transform between White Kyruem and Black Kyurem freely. Kind of like how it does in the movie.