Months ago Yoshi-P said it was not in their plan to put such "potions/magic" in the game, but now who knows?! If there will be areas with several mobs L55-60+ it could be funny sneak through them, praying your Invisible/Sneak effect doesn't wear off.

P.S.
Remember The "Old" Black Shroud"? With its narrow paths, full of True-Sight damned Pug? One requirement woulb be not to show Inv/Snk wear off time...