Communication has evolved greatly over time. People can communicate through speaking face to face, or using hand signals, through the radio or television, or through the computer. As computers take a larger roles in our lives, the idea that they may take over may seem likely, but is typed content better than hand written? Written letters or documents may mean even more now than they did before.
When a person receives a written letter from someone for say a birthday or a get well card, when it is hand written it means more. The person actually took the time to write out a message instead of just giving up the pre-made typed card with a signed name. Or say receiving a letter from someone else just as a way of communicating, it may take more time but it shows that the person cares and really took the time to think about you instead of just sending an email. Sure as busy lives become more hectic and computers are in use more daily, letters or hand written cards may lessen in number, but they'll still be around. It is in many cases just the laziness of people and the convenience of the computer that is allowing typed documents to take over.
As for documentation as sources, or stories, each will have their hard copies, but when it comes to validity, there will always be a need for written statements or signatures or contracts. The problem with advancing technology is the fact that it will now be harder to determine the validity of a document that has been typed. It has become an easy operation to perform to edit a picture or text on-line, thus making it difficult to discern what is legitimate and what is not.
For these reasons and likely more, written text is still as important as before, and will continue to be in the future. The decline in handwritten documents and rise in computed information mostly comes from the convenience, and orderly presentation of typed text. The truth is though that it's just an additional medium to communicate through but it won't take over written statements or information. This is displayed by the fact that speaking may be easier than writing or hand signals but they haven't been replaced because of the needs of the world or those who may be disabled in aspects that prohibits them from being able to communicate in certain ways.