I've long argued that aircraft carriers are losing their ability to be the center of our naval capabilities. They are too big to survive and too few to be able to afford many losses. Combat drones (or unmanned combat aerial vehicles) will, however, extend their usefulness.
Yes, big deck carriers are invaluable in power projection roles against powers without the ability to strike them, but for sea control missions our carriers will face powers with the ability to strike them.
But if the X-47B pans out as a carrier-based platform, the aircraft's radius of about 1,300 kilometers (assuming a third of its range) will allow the carrier to stand off outside of the range of more enemy weapons and still strike targets within range of the UCAV (or UCAS, as this one is called--a "system" is more pricey, I assume).
I'd also argue that precision weapons, which means fewer aircraft are needed to destroy targets, means that smaller carriers could be key air-capable weapons rather than needing the big deck ships.
But since carriers last 50 years or more (assuming they aren't attacked and sunk in combat, of course), it is good to know that they don't necessarily have to be hidden away in an all-out naval war out of fear we will lose them.