By the time this is all over, Gai will still be the most powerful regular shinobi of all time? It's the fact that he became as strong as he did through hard work. He never got any power ups. Not from a third party or anything. No sharingan, no byakugan, no rinnegan, no sage power, no tailed beasts, no sage of the six paths power, none of it. Nobody gave him power, he got it all on his own. Even without ANY ninjutsu or genjutsu. Regardless if he should have died or not in the recent chapters, I'm happy that Kishi decided to give Gai his moment to truly shine and show everyone just how serious and powerful he is. The fact that he nearly kills Rikudou Madara makes him much stronger than even the 1st Hokage. He is a beast forever.