The document is fairly easy to parse, even for us non-lawyers. The filing reiterates the government's position, that Apple has unlocked phones in other cases, has the ability to comply with the court order, and Apple's marketing or business concerns or effect on shareholders are irrelevant to the matter.

In reading the document it seemed to me that the outcome may hinge on whether compliance would be considered "burdensome" to Apple. The government asserts that modifying the software (for this one instance and no other) is more or less trivial, therefore Apple really has no grounds for refusal.

Some comments on HN have suggested the software isn't so simple to produce, but not something I know enough about to speculate. Perhaps Apple's reply to the court will shed some light on this aspect. Fascinating to watch this chess match play out.

I'm guessing in the end the court order will stand and Apple will need to comply. Maybe Apple surmises the same. It's reasonable to believe their protests will garner ongoing public sympathy while cooperating with the FBI under compulsion of the court.