Arch and Debian contributors have tried a good approach for package management..
0: p2pacman - Bittorrent powered pacman wrapper
1: pacman & torrent, feasible?
2: DebTorrent
(0) https://bbs.archlinux.org/viewtopic.php?id=163362
(1) https://bbs.archlinux.org/viewtopic.php?id=115731
(2) https://wiki.debian.org/DebTorrent
I believe scaling this could happen with either: 1) lightweight filesystem\directory versioning support, like how btrfs allows you to mount snapshots. This way, peers could update whichever version of a torrent they have. Or 2) very reliable means to update to the latest torrent release (as reliable as syncing with peers), which afaict means smarter bittorrent clients that can perform DHT-based "crawling". Those recent defcon(?) "hacks" to query peers for similar torrents based on user pools and connection histories (or something like that) would make sense here.
A cool side-note: In one of my few experiences diving into `.git`, I diff'd it before and after making changes to its tracked sources, like adding files and modifying them. It looked like a torrent that included version control data would make out just fine if an updated torrent expected similar data in the same location. Again, a smarter bittorrent client would need to sort some of this out. See also 0': Updating Torrents Via Feed URL. Anyway, most users would probably leave that part out, in favor of only which parts they need.
(0') http://www.bittorrent.org/beps/bep_0039.html
Another cool side-note: This would also allow for easily adding repos from multiple sources... Look at how many ( non-automated :-( ) merge requests com.github/CocoPods/Specs's caregivers have reviewed: 13,331 as of now (0'').
(0'') https://github.com/CocoaPods/Specs/pulls?q=is%3Apr+is%3Aclos...