It is a pretty difficult question when the three specs are different.
The one certain things that needs to go class-wide is Cloaked in the Shadows. And Kidney should be capped at 6s in PvP combat, no question.
Subtlety needs an obvious damage nerf on Eviscerate, as well as less Shadowdance uptime/reset so that they don’t automatically have a dance every single DR without having to ever reset. They could maybe have a dance every DR if that forced them to fight and attack to reset instead of being able to run in circles for the entire DR and still have dance anyway.
Outlaw just needs Restless Blades on 0.5s instead of 1s and/or Vanish not on the Restless Blades list. Just changing this would be extremely huge.
Assa … while many people complain about Sepsis the superior spec right now is Necrolord by extremely far when you don’t play at low/very low rating. Looking at the best version of Assa, so Necro, vs Outlaw, the closest comparable spec, it is a worse version in every single aspect except for the fact that it suffers less from lack of uptime if and when DoTa are running. I’d see where the Outlaw changes lead, and act on Assassination accordingly. But it makes no sense to change something that is just a pure downgrade of something else before you’ve decided where the upgraded version should stand. All that knowing that Necro Assa would be nerfed by a 6s cap on Kidney as it actually benefits a ton from the 7s Kidney.