Whilst Nicky and the Denarians are running around noisily trying to bring on the armageddon, what is Lucifer up to? Perhaps he is running his own team of hand picked operatives trying to supplant the White God. We have confirmation of Lucifer impacting upon Dresden twice, he is definitely keeping a light hand because every time he directly intervenes Uriel cock blocks him. The Denarians allow for indirect intervention but they face off against the Knights a stalemate.

If I were Lucifer I would set up a body of mortal or near mortal beings of power able to use their lovely free will to do my bidding without incurring either Uriel or the Knights intervention. What does THAT sound like. Everyone keeps an eye out for Nicky and ignores Cowl altogether.

I could really care less about what god does what to who.  If they took the body then they must have needed the body to put something in.  And since Butcher didn't bury the body then I fully expect her to be back. So now we have to go with at least one book where Harry grieves because, boo hoo, he misses her. This is the same stew all warmed over as Susan. So now Lara can melt his heart.

What are dead Viking warriors called?
the einherjar
In Norse mythology, the einherjar (singular einheri) literally "army of one", "those who fight alone") are those who have died in battle and are brought to Valhalla by valkyries.

Where do dead warriors go?
Valhalla
The best-known vision of the Norse afterlife is that of Valhalla, the hall of the heroes where warriors chosen by the Valkyries feast with the god Odin, tell stories from their lives, and fight each other in preparation for the final battle of Ragnarök, the end of the world and death of the gods.

In Norse mythology, Ginnungagap (Old Norse: [ˈɡinːoŋɡɑˌɡɑp]; "gaping abyss", "yawning void") is the primordial void mentioned in the Gylfaginning, ...

There's no reason that the two are mutually exclusive. She can be changed and still be Murphy, otherwise no characters can ever experience growth, rise or fall. We'd be on our fourth or fifth Harry by now if that was the case.

Regardless of Jim placing the White God in the Almighty position, he does also acknowledge that other pantheons exist and therefore their afterlives are real in the context of the Dresdenverse. Nic's daughter is in Tartarus, by word of Hades himself. Murphy and Hendricks are in Valhalla by the word of one of Odin's valkyries. Murphy's father is in a purgatory like realm working for Uriel. This is where their souls, the core of their existence, are. It's how the Dresdenverse works.

You have to accept that the author is going to tell their story, their way, using the author's canon for how things work in universe. Or you can read it under protest and be unhappy or stop reading altogether.

The issue may be living memory and for Gard the no-fraternisation rule her employer utilises.

Gard may also be aware that Odin’s time is drawing near, she may have thought she had decades with Nathan, instead she may only see him briefly again at Ragnarok.

I wonder if because of Hendricks’ Gard will tell Harry how to make Einenjharen, so that he raises both Hendricks and Murphy tied to his life. Suddenly days and decades replaced by centuries.

I think the afterlife is dependent upon belief but can be diverted by the white gods or other power, Deidre should have gone to Lucifer, on belief  but ended up with Hades.

I suspect Nick will at some point realise he has been played for millennia by Lucifer and at least one fellow Fallen as fall guys (pun intended) and misdirection. That may be enough for Nick and Anduriel to return to the White God, and perhaps bring the grail with them. That may have been one of his major past objectives, preventing the world seeing him as impotent.

I would agree with that if they hadn't taken the body.

Either Murphy is Murphy  or she's a monster of Vadderung's creation. It would do my heart good to know that my mother was somewhere swilling beer  with someone even if I was forbidden to see her. Which is different then not knowing and having hope replace certain knowledge.

When is dead, dead, in the Dresden Files?  I can write any number of scenarios that work.  But what was the point of killing him if you are just going to resurrect him?

Death loses its gravitas if it is never, really final.  Murphy got killed. Butcher uses it for the emotional punch.  And then he resurrects her.  The whole scene with Rudolph turns out to be about Harry losing his shit because Rudolph made his girlfriend go away. Not because she died, because, well, she didn't.