It sounds from the text of this tweet like Elon Musk plans to continue to do barge landings over the long term:
"Base is 300 ft by 100 ft, with wings that extend width to 170 ft. Will allow refuel & rocket flyback in future."
If so, presumably that is because they can save on launch mass because that requires less fuel. That weight savings can then be used to reinforce the structures of the rocket, give a bit more delta-v to the following stage, have a bigger payload, or maybe just have more fuel margin for maneuvering. It also implies they are confident they can make the barge sufficiently stable for landing in all sea conditions.
Thus the long-range plan would seem to be to launch from Brownsville TX and perhaps land in the Atlantic, in order to have the best distance in which to use air drag to slow the stage.
Can the fuel they would save by doing this be calculated?