Multiplexer that works by measuring voltage on select input?
This looks like another XY-problem. I doubt you can find a mux with this many channels that can be controlled by single wire. Nevertheless, here are some ideas for you.

Ideally, I'd recommend using something like serially controlled ADG731 mux, which requires only 3 pins. However, if you carefully time SYNC signal and supply external clock, you can get by with 2 wires only, thanks to internal 8-bit counter that will automatically stop accepting input after 8 clock ticks.

If you insist on single wire control, you can do it with 2 chips. One is MUX with parallel address input, another is binary counter. For example combination of ADG706 and SN74LS93 will give you sequential access to 16 analog channels.