People have said that history is written by the writers (ie. literate class), but now with a broad segment of the public literate and able to disseminate information broadly through the internet and mass media, will this make the work of future historians easier or more difficult? For instance, is the study of Mao-era china (when literacy was fairly common among the entire population) easier than studying republican or late-qing china? Obviously this is not an ideal example because of the vast cultural and political differences, but it's an example that came easily to me.
I'm not sure it's a question of harder versus easier, just...different. When you have fewer sources, EVERYTHING is relevant. With medieval women, every single word of every single text defnitely or probably written by a woman, and of texts where we think a woman had some influence on the known male writer, gets analyzed half to death in a thousand different ways because we have so little direct access to women's perspectives of the era. Today, one girl's Tumblr account or one celebrity's Twitter feed (ghostwritten or not) might tell us a lot about that girl or that celebrity, but to talk about "high school girls' identity construction" or "celebrity PR" more generally, you would want to compare MANY Tumblr and Instagram and Vine accounts, MANY Twitter feeds and Facebook pages and talk show appearances, etc.
I work on both sides of the spread of the printing press, and sure, it's lovely that I have outside sources attesting to the Existence on Planet Earth of the people I study in the 16th century (beyond the central source or sources I'm focusing on). But that just means I have different stories to tell from those sources than with my 14-15th century ones, or that I have more to take into account.