Honestly, it wouldn't take very much work for Apple to circumvent the lockout mechanism. It might even be possible just by commenting out a couple lines of code. The thing the FBI needs from Apple is the use of their private key.
The FBI wants a modified iOS that will allow them to rapidly try all possible passcodes without getting locked out after N attempts.
My understanding is that iOS's filesystem uses AES 256 encryption. Even if you physically removed the disk, brute force is not an option.
edit Apologies forgot to mention the passcode/fingerprint is tied into the 2 key process.
It would probably make all crooks use long passwords for keychain, but who knows, maybe it would help in some cases.