Well, what does a switch do? How does a physical switch work? Phones -- the old ones -- have big honking mechanical switches, but you can still listen through the things, with a little engineering.
A switch that just twiddles a bit on an input line can be ignored by software.
A switch that controls power might be interesting. But then there's a cable from the camera to the console itself, which could carry some power, and might be used to run a microphone, or maybe the camera electronics, a little bit.
Really, your recourse is to unplug the camera. Or not have one.
Others have pointed out that there are microphones on laptops and tablets (that appear to be off, but who knows?), and many celebrated cases in which reverse-spyware has been used to recover stolen hardware.
This stuff is all around us now. There's no coordinated plan for NSA-like folks to glue it together, or light it up without us knowing, and I think this would be hard, at least for the time being, and doubly hard to do without someone noticing.