Unfortunately it is fully possible for them to pull it out of their ass in short order. As they are being asked to remove very specific features, which if their SD process is as should be, will be relatively easy for them to get to.

Also as pedantic as it sounds, the FBI aren't asking for a "back door" they're asking for the ability to try to brute force it, as Apple's current security software will erase the phone after a number of tries. If Apple could provide an actual back door into their encryption I would be more worried about apples dev practices and what you entrust to them.

It's a fair bet they'll buckle. Which would be a sad day for privacy. But that's the world today.

Geek