The legal question here is really whether the All Writs Act can be used to compel development of new products with specific features law enforcement desires, because that's what it boils down to: they want a custom iOS build with custom security-bypass features that can be loaded onto any phone they want to snoop into.

And when framed like that -- government ordering a private company, without negotiation or contract or even agreed-upon -in-advance compensation, to develop a product -- I don't think there's a chance in hell of it standing up. The question is whether the court that ends up hearing the final appeal will frame it like that.