My 2c:
The goal is longer, thinner wings than usual. Long and thin wings are far more efficient—think gliders and the U2. But beyond a certain width, those wings become incompatible with existing airports and other facilities for handling commercial aircraft. So the idea is to mount folding extensions that are extended for flight, but likely fold when being hangered or navigating taxiways.
And, importantly, this programme is targetting the next generation of single-aisle aircraft.
It was hard enough to convince a few dozen of the world's largest airports to make the alterations needed to accommodate the A380's wings. Demanding similar changes at the thousands of smaller airports where A320-class planes land would be a non-starter.