To say historical evidence is changing, in my view, would be misleading. Historical evidence will always remain to be the same however the popular view of it will change as will aspects of it, such as accessibility, quantity, and quality.
As time goes on, binary code will become the language of historians, and as it does, historians will have more data to filter until they can reach objective evidence. With the coming of computers, social networks, cameras, or technological developments in general, history and the jobs of historians are changing. Many opinions, accounts, events, etc, have come to light that may otherwise have lain dormant never to be explored. That is not to say that these opinions are inherently worth hearing.
Historical evidence will become more comprehensive, nevertheless that does not change what historical evidence is, but rather addresses the faults of historical, historical evidence. As tweets are logged, search histories tracked, cables uncovered, we gather data. This data mustn’t be limited to textual data, for videos, photographs, and audio files are just as easily captured and stored. Data, although not always to the same extent or detail, has always been collected throughout the ages. It will be up to historians to continuously analyze this new data and ensure that we use the right information to build our knowledge.