I've hopped the train to scythe town, but I'm still keeping an eye on the thread. I don't like Xeno's takes mostly because he likes tanks to be interchangeable, to play whatever is FotM for prog and have the same general toolkit to deal with issues.
Personally, I don't really want DRK to get tons of self-healing or support abilities. Maybe buff up Souleater a bit, or something, but giving it a few metric tons of healing like WAR or PLD have would contribute to homogenization yet again, and we are already suffering its' effects. Yes, DRK currently suffers a lot in the defense department. But it shouldn't be fixed by just saying "alright, every tank barely needs a healer now, problem solved".
Honestly, Shadowbringer shouldn't have been an oGCD. Make it a GCD and attach a function to it, like eating into Darkside for a haste buff and a strong hit, or something.