I think there is one more zetsu left. I believe there were 6 zetsu spores, so one was left tied up.
Four to bring back the kages and one for Oro to jump into when he sliced his tummy open. There is still time I think for her return, it would be nice if she returned. Naruto's mom should be a beast in battle too, it would only benefit them.
I too want to see what Kushina is able to do as a shinobi. We saw too little of her strength just helping Naruto gain level-1 Chakra Mode. This was only a small portion of Kushina's capacity. I'm not expecting her to be a complete asset to The Shinobi Alliance, but just "very useful". What can she as a revived shinobi do to help further? That's what I want to see.