Yes, many Christians seem to believe that Satan is currently the king of this world, I think based primarily on the fact that he attempted to tempt Jesus by offering him the kingdoms of the world, and Jesus didn’t dispute that they were Satan’s to give. It certainly seems as though there are evil powers and principalities in firm control now, with small pockets of resistance.

I’m not sure what your eschatological beliefs are but, as a futurist, I think we are heading toward a great tribulation, which Jesus will eventually squash at His coming.