GTX680 is high-end as a single graphics card alone without taking anything else into consideration.

When I or anyone says it is not high-end, we are referring to the Kepler architecture, If it was high-end then it would be the end of line for Kepler until the next architecture comes around, however Kepler is capable of atleast 50% more performance, which will come in a 2048cores Kepler part, it is in comparison to this that the GTX680 is not classed as high end.