How is it grimdark what I am suggesting?
I just want a good conclusion to the Warden's storyline. And them becoming a villain you must oppose is a fitting end in my opinion.
Just because I want the HoF to become a villain and support the idea that Hawke should always have died does not mean I support grimdark stories. It means I simply support stories where the heroes suffers setbacks.
Different strokes for different folks, I suppose. I rather liked the conclusion for my Surana Warden - having left everything behind to be with Morrigan and his son, returning to resume his duties and have a life with his family until he decided to challenge his Calling while she embarked on her own endeavors, with the two of them eventually reuniting post-Inquisition. I certainly see the Calling as a setback.
As for Hawke, that's certainly possible in Inquisition.
I'm certain the Inquisitor and Cassandra will have their own share of setbacks in their endeavors. In my run, I can imagine Cassandra having many trials and tribulations rebuilding the Seekers while Lavellan cements the power of the pro-Dalish Inquisition.