No, Nissan has no plans for a 4Hi to 4Lo shift on the fly shifter. It will still have a Neutral position on the switch that it will have to go through to accomplish this particular shift. You'll have to be stopped, with your foot on the brake, in Neutral or Park (and the computer will look at either wheel speed sensors or vehicle speed sensor to insure no movement) before the computer will allow the shift to occur. Extremely similar to the system currently used on Pathfinders, Titans and Armadas.

But why would you want to do that to begin with? I don't see a point to that.

Also, in regards to the Yukon blowing the fuse, it probably wasn't the t-case actuator that caused it, but rather the front diff actuator that has been redesigned to cure that exact problem. Now it has a seperate harness that has to be installed and spliced into the existing harness to accomplish the same task, but with a newer actuator (just for information's sake, that is).