What suggestion is there that Okonkwo will evolve into a tragic hero?

Okonkwo is extremely headstrong. He follows his passions (and anger) with little regard for tribal rules or courtesy. He is unwavering and inflexible. Okonkwo can't stand change that is not on his terms. Even in the simplest of situations, Okonkwo will have his way. This does not bode so well if something major was to change or go wrong. The arrival of the white man is the beginning of the end for Okonkwo.