Earlier quoted context omitted.
You can drop something that doesn't exist but was announced. Thechnically Skylake support for Win7 wasn't announced, but the effect is the same since there was an implicit expectation that the feature would come.
But I presume dropping support just means not being able to use the latest features. Even a very old system image of windows 7 will run on the very latest skylake. It doesn't need the very latest updates. I doubt they will create a kill switch in a windows update that refuses to boot if the system detects a too modern CPU.
Still better than Chrome endig support for Windows Vista this upcoming April...