A simple idea for power users who need it: check a box, and all automatically downloaded "Online Only" files will automatically get converted to "Available Offline."
This new preference would enable power users to say "let me hold on to all those files dropbox downloads automatically until I decide to set them BACK to Online Only."
This is especially important for customer who do audio/video editing or something similar—where an editing application is referencing many (sometimes hundreds!) of other media files via various folders on Dropbox.
Previously, if a file or folder was set to "Online Only" and the 3rd party editing software tried to access that file, it would simply be unavailable/offline. (Most editing software would notify the user, giving the user time to find the file and it it to "offline only.") But NOW, files set to "Online Only" are automatically downloaded when the editing software tries to access them—BUT THEN they are removed/purged when the software stops accessing them for a time. This forces users to be constantly and unnecessarily re-downloading these same files—which is especially bad if they are large files.
As is, the current approach is extremely disruptive to media editing workflows.