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.