The wiring, hydraulics, and fuel lines must be on pulleys and coils. I’m not saying the design isn’t sound, but it sure is dramatic. No wonder they taxied so slow! The thing would flap like a giant seagull! I bet you could scrape the wingtips with a few good bounces at 2 to 3 knots.
I understand that a combination of flexible wings and active computer control will make turbulence far less noticeable, on the 787, than on earlier aircraft. The wings and control surfaces will be very busy indeed, while the cabin just keeps moving along in a straight line.