It depends on legislation. AFAIU currently kerosene is very lightly taxed, if at all. If there is taxation of fuel or fuel-based payments for airlines, it will

It depends on legislation. AFAIU currently kerosene is very lightly taxed, if at all. If there is taxation of fuel or fuel-based payments for airlines, it will be reflected on ticket prices more than currently. So the airlines can claw some of that back by introducing more efficient planes. But they will be expensive to develop and build, which is again reflected in ticket prices.