Bigger wingspan, higher aspect ratio, flaps, slats, double-wings. A lot of things can be done to make this work. Just because a plane optimized for kerosene-burning turbofans can't be converted to hydrogen and perform as well doesn't mean it is impossible. It doesn't even mean that it will be difficult. All it means is that it will be somewhat different. Different wing geometry, different engines, different fuel systems, different flight envelope. Cryoplane has already been demonstrated with liquid hydrogen, and IMO its performance can be improved significantly using sodium borohydride.