I'm going to have to agree with Verain on this, there are not too many rogue abilties I'd like to see gone. At the moment, the only two spells that I wouldn't cry TOO much about losing are Crimson Tempest and Expose Armor. However, I'd rather see them be changed to not suck than see them gutted. CT just needs to actually do damage for Combat and Assassination. Expose Armor needs to not be completely inferior to Faerie Fire (not take a glyph to apply 3 stacks and not cost energy).
As for what MIGHT happen, it's too early to say. The fact that Arm Warriors no longer have access to Disarm does concern me that Dismantle may no exist in the future.
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Prep: Outside of Sub, Prep probably does not seem too amazing in PvE. However, Sub provides the Rogue with the ability to make the tactical decision to reset their cooldowns. This actually helps add to the Rogue skill cap in PvP.