I'm going to be very unhappyif Kanda comes back. He's my favorite character but the way he died was so beautifully tragic that nothing he can do after that will be able to justify his return.
Also he has no more purpose to live. He would be useless and I think, just be there to make the fangirls happy. It would destroy his character.

As for 'not seeing him die' I'm not trying to be a smartass here but, I think we are so used to seeing 'dead' characters revived that our very idea of 'dead' has changed.
We saw him completely shattered, lean against the wall and close his eyes. Then we saw the image of that lotus flower fade away. I think in any other genre that would be unquestionably dead. I blame Kubo.