Chris

Nah, setting a canon ending is not required for the narrative prose of Astarian writing the book. If they write it in the same style as Tasha's Cauldron of everything, Xanathar's or similar books, it will be a number of flavourful side bar text written in a loopy font that occasionally hints at the person's personality through word choice and the occasional vague reference to personal circumstances without going into too much narrative detail.

Hexblade seems a bit of a waste, surprisingly. Typically the features it is renowned for in 2014 rules, using charisma for pact weapon attacks, are already rolled into the base warlocks pact of the blade feature. Hopefully they rework some of the later class features to make it spicy. Accursed specter being limited to humanoid creature types in tabletop is frustrating.