What brought Nike down is same formula that existed since the beginning of time including Greek mythology.
It is called HUBRIS.
Many people in Nike were in a successful environment and they thought that they were the reason why they were successful. It always happens.
But I had give credit to Nike though because
Under Armour went arrogant only after few years
Reebok went crazy after successful at then end of eighties and gradually went down
Adidas was like that in early eighties when Nike was coming up and kicking their a-s.
Will Nike come back for second run? Yes
Will they get bigger than before? mostly like not. Based on peers mentioned above.
Was that their high watermark? Most likely yes
Did Nike just became Jeff Bezo's bi--h. Yes