Do today's historians play any role in ensuring historians in later times have appropriate material to do their job?

Historians are not archivists — they are different (though related) professions. By and large, historians are about using and interpreting materials, while archivists are about preserving and cataloging materials. (There are overlaps, to be sure.)

So if you're asking, do historians work to make sure that records of today are kept track of? Sometimes we help and give opinions. But by and large, when we do help, we're usually helping make sure records make it into the hands of archivists, because it's really the archivists who are going to do the work of preservation. (Do archivists need our help? In some cases, sure. But they have their own jobs, their own skills, their own expertise. They're not like, waiting around for historians to help them. They do their own thing.)

So just as an example: it is common for historians of science to try and make sure that older scientists have thought about depositing their records with an archivist for future use, and sometimes we help make connections (e.g., people sometimes ask me what to do with their records, and I have a sense of whether it's the kind of collection that would be appropriate for the Niels Bohr Library and Archives, the Chemical Heritage Society, the Linda Hall Museum and Archives, etc., each of which are a bit different in the kind of stuff they collect and maintain). But we don't really do the work of preservation. Sometimes I am sent a list of potential collections by archivist colleagues of mine, and am asked to evaluate their probable historical value. This has been less of a "what will the future find useful" question but a "how unique is this material" question.