I doubt Durkula will survive much longer: His master was just killed by Nale. Durkula attacks Nale. Nale's the secondary antagonist.
Are you serious? What a waste of a character that would be.
I honestly think this book's pretty much over - if anyone's still going to die, it's the elemental and the fiends, and neither of them count. I'll place my bet once more on Zz'dtri, but I don't think any predictions made now are likely to pay off.