What do you mean by "true hut to hut routes"? Only a couple of the AMC huts are open in the winter from what I recall. Carter Notch definitely is, I think Zealand is and maybe Lonesome Lake, but I'm pretty sure the above treeline ones (Lake of the Clouds, Mizpah, Galehead, etc) are shut down in winter...
Who needs huts though? They're definitely convenient, but you can travel in the mountains in winter without them too...