What will happen if i remove the shaft for the

You will end up destroying the transfer case, The transfer case is electronic and not mechanical as the older ones and the speed sensors will throw off the transfer case, if you lose traction to the rear end in the rain, snow or around a corner. The transfer case may activate and deactivate and without the front drive shaft could result in the transfer case to literately explode, also know as grenade. At that point, your looking at a transfer case and may be a transmission. You van runs on RWD unless the rear wheel start to lose traction and then the encoder motor activates the transfer case turning your astro in too a AWD. This was done to save gas, the older AWD transfer case was casing the idle arm to wear out prematurely and the gas economy was 17 MPG and the new AWD system that you have brought the van to 22 MPG. Why do you want to remove it??? if you do i guess you can disconnect the wire harness to the Encoder motor to the transfer case. Good luck and keep me posted.