Even with the public works projects of the New Deal era, there were still a lot more unskilled workers than there was work to be done. That didn't change until WWII, and we definitely don't need another one of those.
Right; its a new world. Today Hoover Dam would be built by large machinery plus very skilled operators. Not by a mob of folks hauling cement around.
There will be less and less room in this brave new world for unskilled labor. Either accept that a lot of people will never work again, or as you suggest, another WWII.
Even with the public works projects of the New Deal era, there were still a lot more unskilled workers than there was work to be done. That didn't change until WWII, and we definitely don't need another one of those.