I believe that all modern commercial aircraft, and many smaller ones store substantial proportions of their fuel in the wings.

Of course, but just because more weight is going into the fuselage doesn't mean the wings are going to "snap off" because the wings are empty. I mean, if the wing tanks aren't needed, surely you could replace them with structure that allows the wings to take the higher loading?

Even in the 747 and A380, the majority of fuel is stored near the wing roots, so the whole idea reads like a non sequitur to me.