The history can be implemented, actually. Librevault stores its data in encrypted blocks, that persist between the file changes. And also, it stores file metadata, that contain the list of blocks, so the file could be recreated on another machine.
Storing two copies of metadata (some KBs each) and all the blocks from both metadata lists will enable you to recreate two versions of the file. As most of the blocks from these files would be the same, then storing two versions of the file in such a way would be more compact, than storing the two files in the filesystem.
So, a kind of file-wise version control is already implemented inside Librevault, but: Librevault client stores only one copy of Metadata (last one) and it removes all blocks, that are part of older files.
In the future, it will be implemented as a part of "archive" mechanism, but it will require a LOT of code.