It wasn't easy to find a good way to route cables for DR's and brakes without the bends and turns giving an issue. With wires for electronic shifting and hydraulic lines for brakes not suffering the same as cables did it will probably be something we see more of.
The frames I've seen with this have access ports and it doesn't seem like fishing a wire through will be a big deal as it was for stiff cables. My own bike, while not completely hidden with the cables has what seems good access to those that are.
And it really does make the frames easier to wipe down. I've started cleaning my bike more after years of not fussing with my other bikes that had cables running all over them.