I've posted this several times, guess it's worth doing again.
There has been no signs that tazik could be nerfed, removed, or otherwise.
As it stands on the PTR, it is still usable, with 450 Engineering.
Has the same range, Damage, off the GCD, everything.
Only thing worth noting is the Animation, as it shares an animation with Lightning bolt, it has been updated to the newer animation, which does look rather pretty.
And as i see it, they would never nerf it, the game is balanced around 85 (Kek, balance) and as the tinker is already almost useless at 85, it'd be more likely that they buff it, instead of nerfing it. (2-5k Zap on a person with 140k isn't going to do much), Or they could just slap a 500 Engineering requirement on it, then the tinker would be completely useless. Seeing as everybody @ 85 already uses springs instead.
Same goes for RBG titles and Arena master. Blizzard hasn't posted saying it would be removed (To my knowledge), only thing even remotely related being the MMR wipe.