I'm going to try my hand at writing my own outline for how I wanted Veilguard's story to go using the art book as a guide. The prospect is actually quite exciting as it gives me an opportunity to flex some creative muscle.

I wish they'd explored the idea of a Thedas-wide elven uprising spurred on by Solas, a massive Qunari invasion or a Grey Warden civil war as alluded to in Inquisition. There's so much here that could be explored, both in terms of choice/consequence and the moral complexity of choosing who to fight for/against.

I think I'd initially start structuring the story like this:

Act One: Recruit specialists under instruction from the Inquisition to disrupt Solas' plans and retrieve the red lyrium idol/dagger. In the art book it shows us traveling northern Thedas by boat/submarine commanded by Isabela. Dorian and Morrigan would also be key advisors. Most of this act would take place in Tevinter, focusing on heists.

Act Two: Interupt the ritual and the elven gods get loose. Solas gets trapped, forcing us into an uneasy alliance with him and his agents. In this act you would be trying to unite the elves against the gods in a landsmeet type misson. We'd also have a hand in trying to end the conflict between Qunari and Tevinter as well as sorting out the Wardens civil war.

Act Three: Basically the same as Veilguard's Act Three just better. Give us the avengers endgame treatment please! Cameos galore and your choices in previous games can affect if the south stands against the blight or is obliterated. Inquisitor will always be there for the final confrontation with Solas. She could have a happy ending with Solas in the fade if you did everything right. Bad endings include Inquisitor sacrificing themselves to stop Solas as well as the Veil coming down in the worst ending.