People don’t normally ride the MTB bikes, but could you imagine a Downhill Cross Country Course through trees n rocks with various tracks to take which could have jumps, mud which slows you, slippery roots etc that change daily so it’s never the same route and obstacles.
Great to have a KODH jersey.
Would work brilliantly with the braking system Zwift could be bringing in.
Slow it down or hit an obstacle that slows you down. 
AGREED! I would LOVE some elements of MTB brought into Zwift. Repack Ridge was fun. Steering, maybe even braking for even just short MTB segments would be great. Maybe similar style routes to what are in some towns where its just a 0.5-2 miles alternative off road dirt route with some jumps and berms.