I've cycled through winters with wind chill in the -15F range and up to a half foot of snow on the ground. So, it is more than doable to do in both those cities.
I don't see why it couldn't be done by almost anyone given that they live close enough to work. Anything less than 10 miles is doable assuming you have a good route.
Maybe proper bike infrastructure could increase the number of bicycle-commuters from ten percent to thirty percent. Think of all the space you could have for your car if there were twenty percent fewer cars in front of you.