You know, I always have high hopes for new books, but this time I have pretty high *expectations* for the next book.
Its been plain for the last few years that GW is aware of NH's lack of specific tools in their current book, and have tried to shoehorn them in with supplements (our heroes or notoriously low wounds, bodyguard rules, bravery shenanigans lackluster, no subfactions) so I expect most of these issues WILL be addressed in a new tome.
The unimpressive stats so far could be due to faction-wide Frightful Touch, or other triggers. It really wouldnt take much to make even the curre t warscrolls much more competetive with subfactions that simply grant frightful touch, or improve ethereal, or improve deathless spirits, etc
Armies like Idoneth and Necrons' pioneering of turn-based effects could see NH getting something similar. Even something simple like a cumulative -1 to enemy bravery each turn to represent the NH's creeping dread could be quite impactful