This post really starts to show the right direction:
Z-Library - "the desktop app", with built in Tor (for seeders safety), IPFS (for p2p distribution), IPNS (to download updated indexes), with local search engine (no SPOF & convenience), optional at-rest file encryption, and some random pining algorithm to let users donate 1-10GB of local disk space to host random chunks of the library.
It needs to be dead easy to let anyone use and contribute.