The Nivida Geforce GTX 980 and the new Titan series are known to give a significant performance boost with NLEs such as Premiere Pro CC. Any news whether the just released GTX1080 will be worth upgrading to?

Double check it's double precision processing power. Those matter more for Resolve and etc. There's a reason why they recommend Quadros for Resolve, cause they have high double precision floating point processing power. Consumer level cards tend to sacrifice double precision for graphics performance.