I'm sure many of us have thought about this before, but someone is now actually starting to make snowshoes that convert to mini-skis. I think they'd not be too effective snowshoes so far (or skis for that matter), but the principal seems promising. For non-icy ascents and mellow descents I'd love to try them! It looks like they're still being machined (vs. molded), so they might be too expensive right now.
http://www.hive-outdoor.com/en/ispo-hive-snowshoes