Given that the D3/D4 is horrendously obese at ~2.8 Tonnes, I doubt Landrover care about that.
I also suspect that if the defender is replaced it will be (as suggested) by a vehicle based on the D3/4/RR Platform/chassis.
http://carsunder500.co.uk/wp-content...8232545650.jpg
Which would be fairly easy, as the driveline has been done...
However a vehicle that needs the body removed to do basic repairs will never be a serious offroader. That said though, a disco-based defender with 35's, beefed up axles and CVs, decent ground clearance and a TDV6 would be quite nice though.
I would do a personal import of a G-Wagen Professional before I would buy a land rover with independant suspension personally.