Granted the Pack Horse (my term) would be heavy. With airless tires, the need to carry weight and to be both field serviceable and folding, I don't know of a way around it. May need to have it re-bent and welded after a mishap.
A standard, as [3] classes of bikes for kids, adults and advanced would be nice (in competitive purposes). I'd sure like to see this made inexpensively and distributed as we today talk of spreading laptops to all kids.
I can't think of a civilian situation that wouldn't benefit. No power, no gasoline supplies in a city like New Orleans? Yet just a few people with Pack Horses and some carts could carry a helliva lot of supplies to others through all sorts of broken terrain.
Without having to wait for "hay-ulp" from the Federal Ediot-Moron Association. Or it's problems.
I know I'd have liked this as a teen and young adult. Standardized bike and gear . . and ingenuity and stamina to win (ostensibly realistic) competitions that would succeed in wartime (as Airborne troops dropped behind the lines), as well as civilian needs. No more races to the rich (with techno, $$$$ advantages), but races to the smartest and toughest.
More than one good shoestring business would come about as we turned our kids loose. Not to mention us graying old farts might come up with something as it didn't cost an arm and a leg to start. We'd need the political will to start changing the way traffic moves in our cities, granted, but I think Americans can handle that.
Hybrid motors and man-steered::man-powered and steered. Can carry a quarter ton-plus. Solid, simple, cast-iron reliable and easy to fix.
I guess the need to make them float, to operate over snow and soft sand could make some interesting solutions to try . . . . shoot, this dog'll hunt (as an idea).