A pair of lightweight, breathable trail runners with decent lugs, like an Inov8 Roclite 295, La Sportiva Croslite, etc. would probably have you covered. If you can get them slightly large, you can pair them with a thin neoprene sock (like NRS hydroskins) and a thinner liner sock + gaiters, snowshoes, microspikes, or crampons and be fine in *most* winter conditions (don't know where you live). The only issue here is sizing them right- big enough to fit liners in the winter, not too big to walk in otherwise. You might get away with wearing the same size by removing the insole when wearing a neoprene sock/liner.
Obviously you're making certain compromises in having a single shoe, but it's totally doable for backpacking/hiking.
All of my backpacking/hiking in all seasons has typically been in a single pair of shoes so far. I wore nothing but New Balance MT101s and MT100s backpacking and hiking (and most of my running) for at least 3 years. Now I like the Roclite for backpacking but more minimal shoes for running.
Obviously skiing, climbing, and seriously cold weather are different...