Superbolide is better than Holmgang and Living Dead. By a mile.
Superbolide puts you to 1HP, but then stops ANY damage you take for the duration.
Holmgang/Living Dead only stop you going below 1HP meaning that to be healed up, you have to not only be brought back UP from 1HP (Since the time you use these are to one button mitigate Tankbusters that hit for more than 100% of your health) but also have to counteract the damage that is being dealt through the duration - Such as Tankbusters that aren't just a single instance of damage, or boss auto attacks.
Living Dead being even worse because you NEED to be healed for 100% of your max health (Which means you're actually getting worse survivability by gearing up and getting more VIT...) or you die and if a trigger happy WHM Benediction's you right as your health drops down, they remove the effect meaning you can get smacked a second time and die...
This isn't even accounting for the fact that immunity such as the kind that Superbolide/Hallowed Ground gives also allows cheesing of mechanics because it will also prevent debuffs being applied to you. Such as ones that would require a Tank swap to deal with otherwise.
Wut?
The only CD that had its duration changed, was Vengeance. It went down to 10s duration like the other 30% DR skills.
Not only that, but every single Tank now has a short CD active mitigation skill. Sheltron got buffed to now blocking all attacks for 6 seconds, up from 1 instance. TBN got buffed up to 25% max HP shield up from 20%. WAR got Raw Intuition for 20% DR with 25s CD. GNB got HoS for 15% DR.
Rampart is unchanged. Shadow Wall is unchanged. Sentinel is now 120s CD down from 180s (But 30% DR down from 40%).
CD's are no more important than before. In fact, they're less important, because now everyone's running around with free 20% DR from the new Tank Trait, with ridiculously short CD 15-30% DR active mitigation skills and heck, all OT's can now provide 10-25% DR active mitigation skill too!
So, baseline, without factoring in any actually costly CD's, Tanks will be able to sit at 45%+ DR for any Tank buster (Considering that before, people were alternating Rampart + Vengeance for 50% DR and Holmgang for 1 button TB mitigation... Basically, everyone's getting a free Rampart + Vengeance on like 15-25s CD's...)
The only new decision making is that Holmgang can skip fewer TB's now with its increased CD. Though, given how much mitigation is now so readily available, I don't think it's likely to pose much of a problem, unless Savage encounter TB's are now requiring 90%+ mitigation to survive (Meaning Rampart + 30% skill + active mitigation + OT support) - At which point, GNB will be deleted from viability due to their crap mitigation skills.