Re:
Expensive! But, it will likely get cheaper and there might be some advantages and you could do some interesting things with a programmable electronic system.
There's no cables to gum up and with hydraulic brakes and electronic shifting, there's no cable friction anywhere.
The thin electric cables can be routed more easily.
A system that allowed you to program the shift distance would allow you to use the same mech and shifters with any cassette spacing.