Which will be tiny.
Videos, audio and photos and game media will take the bulk of the space. Of those - only photos and a proportion of the videos are likely to be totally unique to a user.
Videos, audio and photos and game media will take the bulk of the space. Of those - only photos and a proportion of the videos are likely to be totally unique to a user.
Consider that Dropbox gives you 50gb for the basic plan. I'm guessing most people don't back up videos, games or their OS using that space, but rather back up their documents, projects they're working on in whatever field, photos, and music.
Of those, only with music is there a chance to use deduplication, and that's assuming you can figure out two music files with different ID-tags are the same.
(Come to think of it, in my Dropbox, music easily takes up 70% of my quota, so maybe is is worthwhile after all.)
It would be interesting for Dropbox to release numbers on how many music files are identical between different people.