Bitcoin as an retirement plan, bitcoin to secure the future of your kids, and now bitcoin as a wedding gift. Whether or not bitcoin replaces cash in future, it looks like the trend of gifting bitcoin instead of cash at weddings is definitely going to catch up and more wedding registeries would be adding bitcoin as a gifting option.
People who are not into bitcoin might not appreciate getting a volatile currency as a gift, and might never use it, thus adding it to the list of lost coins, but I think people who are already using bitcoin or would most probably use it in future then bitcoin instead of cash is the apt wedding gift for them.
http://www.marketwatch.com/story/would-you-give-bitcoin-as-a-wedding-gift-2017-06-27
I think using bitcoin as a wedding gift is not a nice idea because it is not yet famous compare to conventional money so there's a tendency that they don't know the significance and usage of bitcoins. Bitcoins are not a sentimental gift also, maybe they will less appreciate it. Instead of giving bitcoins as a wedding gift, try to withdraw that bitcoin and buy something special as well as usefull for them.