Since the community seems about 40/60 liking/hating Breath of Sindragosa (as far as I can tell), I think Blizz should try their hardest to make both Obliteration and Breath of Sindragosa builds both viable, rather than Obliteration being significantly behind.
My idea for a fix is thus-
Killing Machine: “Your auto attack critical strikes have a chance to make your next Obliterate automatically critically strike and deal XX% more damage.”
Since BoS got a straight buff via the rune generation before and after, Obliteration should get its own buff. You could even bake the “and deal XX% more damage” into Obliteration if you don’t want it to give a bit more extra damage to those using Breath of Sindragosa.
…And while I’m here.
-In my opinion- the level 56, 60, and 90 talent options seem clunky/lackluster.
(These might be somewhat wrong, since Breath of Sindragosa made me drop Frost DK at the start of BfA.)
Inexorable Assault does very little damage, and is boringly passive.
Icy Talons is ridiculously difficult to keep up
Cold Heart is clunky imo, and just isn’t as impressive as the legendary from Legion was.
Avalanche is boringly passive, and does relatively little damage.
Frozen Pulse is the most boring passive I’ve ever seen. It’s “oh, you’re starved? well, here’s some extra auto attack damage so you can feel better”
Frostscythe is FUN. I LIKE it. Too bad it does literally nothing single target, so it’s useless most fights.
Gathering Storm is like Cold Heart in that it just clunks up the rotation.
Glacial Advance. Boo. Nobody likes it, and it does like 0 damage. Get it out.
Frostwyrm’s Fury seems odd. The 3 min cooldown doesn’t line up with Pillar of Frost, it’s just a big burst of damage, then it’s gone. It’s also a GCD just gone. I don’t know how I feel about it.
So there, there’s my opinions and possible fix. I -LOVED- Antorus Frost DK, and I honestly miss it. Hopefully Blizzard does something else, other than just loving their BoS child more than Obliteration.