Likelihood that Rin becomes an Edo:

[jaykuhz]

She's fodder to the war, physically.
No need for her unless it's talk-no-jutsu. But we have Kishi's flashback-no-jutsu.

 

[Curteth]

She's fodder to the war, physically.
No need for her unless it's talk-no-jutsu. But we have Kishi's flashback-no-jutsu.

...unless it's sole too find out she is sill alive... In which case we may have Zetsu too possibly thank ...

Edit: only Kishi knows she's fodder... She could have been trained much like Tobi was found out too have been...