Become a snowbird and move to Tucson or Albuquerque for the winter?
OK, that might be more expensive than annual chain and cassette replacement.
If you've got a basement with a drain, you could spray the drivetrain with water every day after your homeward commute. I'd use a wet lube so it wouldn't wash off every time. Or a bug sprayer with warm water, in a designated spot in the yard, followed by bouncing the bike to shake residual water off the chain.
You might also touch base with the Winter Cycling forum on this site.