Hi Kimberly!
Thanks for visiting the Moms Panel with your question. I'm so glad you asked, because it's something I hadn't thought about before!
I haven't yet had the opportunity to check out the reimagined
Disney Magic, so I checked in with my fellow Moms Panel panelist Marcy. She recently spent time aboard the Magic, and gave me some insight into your question!
As you stated, on the Dream Class ships (the Disney Dream and Disney Fantasy), there's a panel on the wall that controls the electricity in your stateroom. All you need to do is insert a card, such as your Key to the World Card, to turn on the lights. I usually use something besides my Key to the World Card, so if I need to run out for a bit I don't leave my family in the dark!
Marcy was in an Oceanview Stateroom with Verandah on her sailing, and there wasn't a slot on the light switch to insert a card. She also checked out a few Oceanview (non-verandah) staterooms, and they were set up the same. It looks like you can keep your cards in your wallet or lanyard, because they won't be needed to turn on the lights!
I hope you enjoy your voyage on the Disney Magic - the new renovations look amazing, and I can't wait to see them for myself! Happy sailing! - Diane W.