Just recently I read a very interesting article about difficulties of storing digital movies comparing with film movies "Will Today’s Digital Movies Exist in 100 Years?" (read more about this). It surprisingly says it is easier save film movies for a century than digital ones, due to software upgrades. It's called "100-Year Archive Dilemma".
What does it means for you and your wedding images? It means if you would like to archive your wedding digital images for more then 10-20 years, nobody can guarantee that in 10-20 years new versions of a program will be be able to read your images files. And you will have only disk or a flash or cloud storage with nonsense files ...
"The software that created the data has limited backward compatibility, so newer versions of a program may not be able to read data stored under older versions."* (read more about)
Even more, you can't rely 100 percent on online archiving services even for a couple of years. For example, once popular Web site where professional photographers archived and sold their photos, is now gone, completely. Shockingly, they informed user to download images in 24 hours and totally shut down service after just 10 hours(!). It was a Digital Railroad...** (read more about)
So, until now the most reliable way for images archive is PROFESSIONAL LAB PRINTs. (And most beautiful, too :))
That is why I always suggest include professional photo book/album with archive quality photos in your wedding photo package.
And if you are a person who care about your legacy you definitely will appreciate it over time again and again.