It seems to me Black can hold the diagram by ...Ke8.
I considered the plan ...Nc5 and ...Kd7 after but it fails because of ...h5 undermining the knight. I will analyse it tomorrow and give you my thoughts, but it looks like the white king has no access through the pawns.
I am currently learning the grunfeld, and am interested in learning some of the endings that arise where black has a queenside majority and white has a central majority. If anyone has any ideas or examples of this ending they would be greatly appreciated.