Apparently they will now:
Unlocking for Domestic Usage
Sprint will unlock a device from Sprint's network under the following circumstances:
- Any associated Service Agreement, Installment Billing Agreement, or Lease Agreement has been fulfilled including payment in full of any applicable early termination fees or end-of-lease purchase options
- The associated account is in good standing
- The device has not been reported as lost or stolen, associated with fraudulent activity, or otherwise flagged as ineligible to be unlocked
Generally, if you have a device that was launched prior to February 2015 and it is capable of being unlocked, Sprint will provide a bill notification and/or text message when you are eligible to have your device unlocked. The bill notification will direct you to Sprint Customer Care who can assist in efforts to unlock your device.
For domestic SIM unlockable ("DSU") devices launched after February 2015, Sprint will automatically unlock the device when it becomes eligible.
For inactive devices, customers must contact Sprint Customer Care to request that their DSU-capable device be unlocked and may have to take steps to perform an over-the-air update to ensure the unlock programming has been relayed to the device.
http://www.sprint.com/legal/unlocking_policy.html#!/