One thing to bear in mind is that the availability of resources both in its archiving and in its production is diffused to an unprecedented degree in human history thanks to advances in literacy and technological developments such as the internet. There is no scholar class that has exclusive access to literature. Will certain issues fall through the cracks? Absolutely. But whereas a historian of, for example, Mesopotamia, might have a very finite number of resources to work with, a future historian looking back on our own time will have everything from NSC policy papers to New York Times magazines to tweets (the value of this is a question I'll gladly leave to future historians).

Going off of that, the internet is doing a relatively fine job of archiving the mundane aspects of life. As the saying goes, the internet doesn't forget. Clearly there will need to be active archiving processes for less public matters such as governmental records and perhaps a more centralized means of collecting these mundane aspects, but the trend seems to be positive.

Historians such as Roy Rosenzweig, author of Clio Wired, have argued that historians should take a more active role. He argues that we have a duty to future historians, and perhaps more importantly, academic history without a presence on the internet might well be forgotten and ignored as technology advances. Ultimately, a lot of the archival process falls to the curators and archivists, but Dr. Rosenzweig does make a convincing argument for historians taking a more active role in this process, be it in contributing to Wikipedia or other methods. He does make the argument that archiving and preservation is a responsibility that historians should take on; some older and more conservative/traditional historians may take issue with that. There is an argument to be made than a historian taking on an active role can be risky as we insert our own biases, but I'll leave that to you to decide.

source: Roy Rosenzweig Clio Wired, 2011.

It is not a historian's job to preserve the present for future historians. That is more an archivist's job; they are very different professions in this respect. Historians study and interpret the past. Archivists try and maintain the past (and present) for the future.

Separately, a historian would be very wary of presuming to know what kinds of history the future might be interested in writing. If historians in the 19th century had been solely in charge of knowing what to preserve for the future, we would be largely limited to the writing the histories of white politicians and their wars. What we consider important today may be of no interest to the historian of the future. It will be up to them to determine what is important in the long-run — that sort of thing is very hard to see from the perspective of the present.

It will be up to the historians and whomever of the far future to figure out how to read our language if they somehow lose the ability. (One would have to imagine quite a catastrophe for that to be the case, given the hugely redundant sources in English as well as copious dictionaries, grammar books, and so on — the kinds of things we tend not to have for "lost" languages like Linear-A.)