According to ITWorld the early tests on the Skylake-C showed that it was going to be a killer chip, but instead it was bumped off.
There will be a broad range of Skylakes for handhelds, tablets, laptops and desktops, many of which are already announced, but there will not be a Skylake-C.
The reason appears to be that wafer yields from Skylake-C were lower and this meant a combination of increased cost and lower yield.
Intel has had enough headaches with 14nm as it is, and there is the upcoming Kaby Lake processor, which we do not know much about.
Chipzilla said that it was responding to market demands.