My winter wheels are actually like this, and a whole lot worse. But for the price (free, with good winter tires!) I didnt mind.
There are a few DIYs out there on how to refinish them. Basically involves heavy duty paint stripper to remove the existing clearcoat and paint, then you sand and polish the corrosion off the wheel, then you re-paint and/or re-clear them. You could leave them raw aluminum but would need to keep a good coat of something on them at all times or else they will corrode again.
Mine are so bad that ANYTHING would be an improvement, so Im going to try to strip everything off, sand/polish and then clearcoat them.
Going forward there isnt much you can do....once the corrosion is under the clearcoat, its just going to spread like a bad disease. I suppose if it gets really bad enough it could cause a structural issue with the wheel, but that might take a while.