In the medium term, my guess is that they want to force Apple to alter the code in the secure enclave of all iPhones manufactured so that in the future the phon

In the medium term, my guess is that they want to force Apple to alter the code in the secure enclave of all iPhones manufactured so that in the future the phones can be backdoored on demand either by Apple under warrant or the FBI themselves. In the former case the NSA would of simply acquire the necessary keys by whatever means they preferred. At the moment, for phones with a secure enclave, this isn’t possible: Apple intention was to create a system that they themselves can’t crack precisely in order to prevent anyone else from being able to crack their phones. It’s possible that the NSA has physical attacks that can work around the secure encalve now, but these are always vulnerable to future improvements in the devices - the government would vastly prefer to have some kind of mandated access. Winning this case is a step along the path of building up the legal precedent for them to be able to do this. Sure, by itself it won’t be sufficient, but they don’t expect it to be - it’s a stepping stone along the route.