My gut feeling is the .gov simply wants access to every iPhone like they have with so many other phones.
That is the endgame in my opinion. My hunch is they are going down two paths to get there. Use the courts or public opinion to push for legislation by manipulating public opinion.
BTW, I posted on a another thread San Bernadino County said yes, they did change the passcode but it was at the request of the FBI.
https://mobile.twitter.com/CountyWire/status/700887823482630144
“The County was working cooperatively with the FBI when it reset the iCloud password at the FBI’s request.”
A little detail left out of the DOJ’s footnote.