What do you reckon the classification systems will be like in 100 years?
Are you asking about the classification systems in the libraries? If not, your answer is not possible to answer in any way. Even if we talk just about library classification systems, 100 years ahead is too much to predict anything. But if there are still organized collections of documents in 2118, some kind of classification is most likely still needed. Even if the libraries and the data bases are not anymore conducted by humans but by machines, there must be ways to analyze the documents according to their contents. The complexity of the data in 2118 probably means, that today's classification systems are not enough, much broader and more complex systems will be needed.
To take just one example, music, which is my area of expertise, one can easily understand, that "music in 2118" is for a large part totally different to "music in 2018". We still have the classics of each century and style, but there will be a lot of new instruments and genres in 100 years. Some of them are probably something that we simply cannot imagine this day.
I do believe that there still are library classification systems in 2118, but they differ significantly from today's systems. They are operated by machines and their accuracy is far beyond the ones possible now. The structure of "knowledge" will be different and contain several levels and objects we cannot imagine now.
Heikki Poroila (unfortunately not around in 2118 anymore)