I applaud the OP for thinking outside the box. Though I haven't considered the infrastructure question as much, it is clear to me that riding in the winter is always going to be something left to the nuts like me unless something better than studded tires comes along.

Maybe it's a semi-enclosed trike. Maybe something with electric assist.

Anyway, the idea of mingling with cars on the streets scares a lot of people. And frankly, there are streets I avoid like the plague. My guess is that a fear of getting hit by a car is one of the major barriers that keeps people from commuting by bike.