Technology with electronics has made big inroads with engines on the modern 4WD

Perhaps...but it requires the R&D investment from a manufacturer and a viable business case from same, to make it to market. But its already happened with auto front hubs - how many new fourbies do you see these days with hubs you have to get out and lock yourself? All done with the push of a button, you can probably bet that the next step for the ubiquitous transfer case will be something along the lines that you have mentioned, all governed by electro-wankery, possibly linked into the ESC programs and whatnot so the car's computer knows precisely when it needs hi/lo or whatever and the driver doesn't even have to think about it.

Also bear in mind that "proper" 4x4's aren't volume sellers, they are a niche market vehicle by comparison to the rest of the car market, so the impetus to bring such an expensive and sweeping change to one of the most fundamental systems of the vehicle won't be seen as being pressing or urgent as one of the cut-throat volume selling segments like say, small cars or SUV's.

My 2c (GST free)

I thought VW had put it onto one box with the crawler gear in the T4 4motion?

There are a number of sophisticated 4WDs out there if you want them.
Constant 4WD, electronic traction control, push a button for snow another for mud or sand etc.
Give me a Troopy any day – a real truck, big and tough with everything manual.
I’m a 64 YO dinosaur and when I get to the stage where I can’t change gears anymore I’ll give it away.