Almost anyone has the capacity to run at WR marathon pace for at least some distance. All that stops them from doing it longer is self-belief. The mind is weaker than the body and it gives in first. You will have experienced this during workouts when you think afterwards that you could have done more or gone faster.
I am going to abandon high mileage training in order to devote more time to train my mind which will give me greater gains. If I can reach a point where I believe 100% I can beat the marathon WR then I will go out and do it.