I did not know that there was a Naruto discussion thread here. Anyways, I think that Kurama's Yin chakra will return to it, and Naruto will unlock the ability to perform genjutsu (since that's what Yin chakra is used for).
Alternatively, Kurama's Yin chakra released from the shinigami's stomach will be absorbed by the Jūbi and used to fuel another evolution, making it even more difficult for Tobi and Madara to control it. This evolution will probably force Tobi to use Rinne Tensei and bring Madara back to actual life, giving him the opportunity to become the Jūbi's jinchūriki. However, upon seeing Hashirama on the field, Madara will deny the opportunity to become the Jūbi's jinchūriki and seek a battle with him, eager to test his strength. More on Hashirama and the other revived Hokage below.
Anyways, now that the four Hokage have been revived, what are the odds of any of them breaking out of the seal, ala Madara style? I'd say that the odds of that happening are extremely high. I'd say that among the four of them, Tobirama will break the seal first, courtesy of him developing the Edo Tensei technique. Yes, Orochimaru and Kabuto have further developed the technique, but I think that the way of undoing the seal placed on them remains the same as when he first developed Edo Tensei. After Tobirama, I think that Hashirama should be able to break the seal placed on him. If Madara could break past Kabuto's seal, then I'm pretty sure that Hashirama could do the same. Hiruzen's presumed mastery over all of Konoha's techniques should help him get out as well. Minato's knowledge of seals should help him in this as well.
Also, this is a minor detail I noticed, but after opening the shinigami's stomach and getting his arms back, Orochimaru evacuated from his old body and moved into a White Zetsu. Since Zetsu was created from Hashirama Senju's cells, do you think Orochimaru will learn how to use Mokuton (Wood Release) techniques?