A true captain can stop a ship if it's heading into rough waters, even if he can't turn it around. A single executive order could cause everyone at NSA to take a paid furlough, just as a single executive order could close Guantanamo.
Obama has sworn, twice, to preserve, protect, and defend the Constitution of the United States. If there's something truly worth defending about bulk collection, something so important that it's worth compromising the Constitution, he should tell us why he's breaching the trust our electors placed in him.