It will make combat viable but sub will most likely still be the go to specc. Good think is - all 3 speccs will be pvp viable.
And I really think they will buff this and that about sub. (they said they would look at the mobility tier again) and I very much hope they buff hemo/Backstab.
With that I think rogues would be in a very good place and have 3 viable pve and pvp speccs.