The possibilities really aren't endless.
It's one of two things:
1. The GTX680 is actually mid range and the GK104 codename is the valid piece of information. The 680 name then loses its high-end meaning, though only in the long run, whenever GK110 is release.
2. The GTX680 is actually high end and the GTX680 name is the valid piece of information. GK104 then loses its mid range meaning, again until GK110 is released.
All this is pending the release of GK110, but until then, no one can argue that the GTX680 is mid range. It just isn't. It might become mid range at some point, but only if GK110 is actually the same generation. If GK110 simply supersedes GK104 with the name of GTX780, then it just becomes the new generation high end, and GTX680 becomes the old generation high end.