"There are plenty of flat approaches up drainages that have enough packed down snow to ride a bike on, where this would work great... if it was a fat bike."
My first experiment with electric assist took place in CB in 2001 with a Currie Drive and SLA battery throttle control system mounted on an XACD aluminum frame 29"er with Nanoraptors. I got it together in the early spring so there was still a lot of pack and rode out of 420 Belleview down 135 and turned up towards Brush Creek. At Veltries Ranch the road turned into snowmobile track and I thought what the heck and hit it. To my surprise the bike kept going and in fact went quite well to the point where I remember laughing out loud.
Since then I have ridden on packed snow trails with 2.1's or a little better at low psi many times. I feel if it is packed, and certainly if it is just a plowed access road, there is no need for fat tires. However for unconsolidated snow conditions fat tires work much better up to the point that they don't. Mike Curiak is pushing that envelope every year and is able to ride in powder with 5" tires and super wide rims at like .5psi.
However the Scott bike above has skis aboard so it is not meant to ride on unconsolidated snow, that's why you have the skis. But I do think it has studded tires, or at least should. Big problem would be keeping it secure at the trailhead while you are doing laps.
As an aside I ride my drop bar front hub bike with 45c's @35psi here on and off the beach just about every day as well as the sandy single tracks in amongst the dune grass. The front wheel drive feature is most of the reason it works but it has to be in sync with active pedaling to work at 100%.