It's IMO an existential threat for lemmy.world. Sure, a big corporation could handle it, but here we're talking about an instance which will be forced to shut down if copyright lawyers knock at the admins' doors. Federation is a double-edged sword, it means technically you also host all the content that's being published on instances that are federated with you, so in particular if piracy communities don't do a good enough job cleaning up lemmy.world will be liable for that content since it will be physically on this server too.
And what did Nintendo do? DMCA people? Yes, thats what they did. A DMCA is a piece of paper that says "remove x shit right now". It doesn't mean anything else, its a promise of consequence. The Pirate Bay is in no way similar. Are we hosting content links that directly link to torrents? No? Cool.