Reason 1: Sage techniques can harm Madara.
Reason 2. Taijutsu can harm Madara.
Reason 3: She needs to pay him back after ripping her in half with his bare hands.
We all know that only two things can harm Madara, sage techniques and taijutsu. And Tsunade just happens to be one of the most talented if not best taijutsu user in the story thus far.
The hints Kishimoto left behind just makes it so obvious that she will obtain it.
Reason 2. Taijutsu can harm Madara.
Reason 3: She needs to pay him back after ripping her in half with his bare hands.
We all know that only two things can harm Madara, sage techniques and taijutsu. And Tsunade just happens to be one of the most talented if not best taijutsu user in the story thus far.
The hints Kishimoto left behind just makes it so obvious that she will obtain it.