Well, it seems my prediction about Nishi showing up to deliver the "final blow" was right, though obviously it didn't kill Nurarihyon. I guess it'll come down to Oku and/or Tokyo team taking this thing down (assuming something else completely unpredicted happens).
On a side note, I'm not expecting Kurono to be brought back any time soon. It seems to me his death was, in a way, a plot device to get the other members of the Tokyo team to grow/mature. Katou obviously is acting all Kurono-like, but he was like that from early on in the series anyways. I'm predicting Kurono won't be back until we see Reika and the others growing a bit more self-reliant. Let's face it, prior to this they all heavily relied on Kurno (especially Reika).
Ah well, maybe they'll all get the character growth while fighting Nurarihyon and Kurono's return will be "go". :p