[Hela marches her army of dishonored dead and has a battle at Bourne Woods, in Nornheim
(or else it is the Vanir or a coalition)
Meanwhile, the Naglfar crashes into Karnilla's palace (or some other small palace).
The assault at Bourne Woods presumably is unsuccessful, thwarted by Thor, Sif, Warriors Three, and various other Asgardians.
The dark elves are allied with Hela, and we need a McGuffin yet (if we don't want to use the ones offered by Andrew Lawden) to get Thor down to Svartalfheim to battle Algrim. We also need a McGuffin to get Jane into a scene with Odin. The dark elves might attack Midgard, but it's not clear what the motive is.
Surtur is manipulating things behind the scenes. Likely he is working through Hela. Surtur changes Algrim into Kurse, perhaps indirectly.
Hela sees this as a chance to gather more souls. Malekith sees this as a moment of power vacuum, with Odin's power waning. Surtur sees this as a chance to get back at Odin for the clash they had millenia ago.
<more plot we haven't figured out yet that brings Thor and Kurse together. Also, Tyr shows up.>
<Alice Krige does something. I guess the most likely idea is as Hela.>
<something happens at Stonehenge. Maybe a portal to Alfheim, maybe to Svartalfheim?>
Perhaps Thor decides not to live in Asgard at the end of the film. (Avengers Tower is an obvious housing choice.)
I am totally on board with 100%. I a few minor dissagreements though, just a few,
Other than those two things (one of them just being one I am having trouble understanding) I am an board.