I wouldn't be so sure. There are still some massive tech problems to finish out before it's even viable to run both engines with. Pressurization and anti ice are both huge problems. In 99% of airliners, pressurization and anti ice bleed air is coming off the high pressure section of the turbine compressor section. Also electrical and hydraulic power. All currently come off drive generators from the turbines. Making the flip to hydrogen will take a massive amount of engineering to overcome some pretty glaring problems. Theres a long way to go still.