I think what you're suggesting is already possible (in a different way) not by using the blockhain, but by crawling bittorrent's DHT.
Either of the solutions, will let seeders and leechers communicate in a decentralized way, but if there is no one with the original files, it won't work.
So, in this case, nyaa facilitates the seeder/leecher communication, but if the main site is shutdown and users who have the files are not willing to seed the torrents again then the source code is useless.
Crawling bittorrent's DHT is mentioned in this paper [1]:
This paper presents two kinds of attacks based on crawl-ing the DHTs used for distributed BitTorrent tracking. First, we show how pirates can use crawling to rebuild BitTorrent search engines just a few hours after they are shut down (crawling for fun). Second, we show how content owners can use related techniques to monitor pi-rates’ behavior in preparation for legal attacks and negate any perceived anonymity of the decentralized BitTorrent architecture (crawling for profit)
Either of the solutions, will let seeders and leechers communicate in a decentralized way, but if there is no one with the original files, it won't work.
So, in this case, nyaa facilitates the seeder/leecher communication, but if the main site is shutdown and users who have the files are not willing to seed the torrents again then the source code is useless.
Crawling bittorrent's DHT is mentioned in this paper [1]:
This paper presents two kinds of attacks based on crawl-ing the DHTs used for distributed BitTorrent tracking. First, we show how pirates can use crawling to rebuild BitTorrent search engines just a few hours after they are shut down (crawling for fun). Second, we show how content owners can use related techniques to monitor pi-rates’ behavior in preparation for legal attacks and negate any perceived anonymity of the decentralized BitTorrent architecture (crawling for profit)
[1]: https://www.usenix.org/legacy/event/woot10/tech/full_papers/...